20 eC Geology Series MUSEUM VOLUME 54 NUMBER2 26 NOVEMBER 1998 ———————————————————————————————————————————————————————————————— The Bulletin of The Natural History Museum (formerly: Bulletin of the British Museum (Natural History) ), instituted in 1949, is issued in four scientific series, Botany, Entomology, Geology (incorporating Mineralogy) and Zoology. The Geology Series is edited in the Museum’s Department of Palaeontology Keeper of Palaeontology: Prof S.K. Donovan Editor of Bulletin: Dr M.K. Howarth Assistant Editor: Mr C. Jones Papers in the Bulletin are primarily the results of research carried out on the unique and ever- growing collections of the Museum, both by the scientific staff and by specialists from elsewhere who make use of the Museum’s resources. Many of the papers are works of reference that will remain indispensable for years to come. All papers submitted for publication are subjected to external peer review for acceptance. 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(Geol.) © The Natural History Museum, 1998 Geology Series ISSN 0968-0462 Vol. 54, No. 2, pp. 109-163 The Natural History Museum Cromwell Road London SW7 5BD Issued 26 November 1998 Typeset by Ann Buchan (Typesetters), Middlesex Printed in Great Britain by Henry Ling Ltd, at the Dorset Press, Dorchester, Dorset Bull. nat. Hist. Mus. Lond. (Geol.) 54(2); 109-130 ANE WUMTUNPRAO Caradoc brachiopods from the Shan Stafes,.!5 NOV 1998 | __ PRESENTE Burma (Myanmar) GENERAL LIBRARY L.R.M. COCKS , Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 SBD ZHAN REN-BIN Nanjing Institute of Geology and Palaeontology, Academia Sinica, Chi-Ming-Ssu, Nanjing 210008, People’s Republic of China CONTENTS VO P SIS sees 2. each teres cates sc tae ves Amand. dered eee hd cc hme 2, 2, os 5sc erence eae eas dee ia tae lec nual lan ghee. 109 IUi\aCoYs LN C{ (0) 0 Seale er Ree Seer ore eee coer ace ecco reco Seen ae Per Se PRR ROO: Sern cate eC RECC CRC OR EE Rene eee Sere ereces Reeeece scrececre eee 110 Brachiopoditaunalotthe Naungkan pyill Groupyam ie clita em tS eeresesresc teen ce ee eee ee ee Pete eee 110 ENGR OVE WOTEY LEAN) OC Pescretpecer Merce RRO CEC ACNE cate Bec nL cr cE occa CPECEr Ree ooo eC aoe Ae Ce Races Cao Ceo nCE RC cee norc eeu oaseseccnceee 111 AU AL ASS OCIALION Spies nasa cedures ste Bewtens eetraa waste oasuttosea we esas Wott cre ata snaes Sam ehe secret dec stays stavesmpeasessasi dasceasacosastosieesescersousserseavines 112 Palacoceo praphicalianalySis:ceeccutccc cect sce cs cts east seat oa ceesvar ces eete ree ners -co Reena oe PR a grt Sees So STRE CRTC aay nee cc sey ome eo 112 SyStEmMatlCpalacOMtOlO Oy ceca eeescsczs cas prasceosscacansascees swGseeselsSasaeussuenee oe oeeaCeeINSEAGM Tap ntsntvascace¥s evel iel sue sussel ot anedhstoadstestcaneNuaee tyes 113 Supenamily Mein suloidea Menke mS 2 8ye scekecrscs.ct este ca career nawarte esr ar raete eet cca nesiane etttastawtece sescaetsre fs seetenertseniererees tt yaes 113 PAIGCOBIOSS@ OOS Ps, csexececse sees so one cae se cadets ae Sue Seed ecw ic Sue SEM EATEN ERENT Tv ca de OT OREO SSC e TEST SUERTE ETT 113 SU oeraiearo ally Onion oleen \WWOroGhiennGb; 1193512) cacescarcnsecaosendorocsascoccoccecoecaqsoageanesoonnecaccooc cascensoedecosesonapa5edoecAcoadarnnenderce-acaeeceanedaccona9 114 PIGEStOMYS TAUNZIGIENS ISI INCEAs 9S GO) yeeececesectcevceccces x tncssccesnecectsvescersontceuseincrssecdvcvarersceusee cette ae ET 114 INicolella’ sylvatica (REEG, L936) -caccxcoxceccareesees cones ene oe ea te cee eee ee ae ac Bie at em ean dec Ponti uane ator etesesesubstisessaperey’ss 114 INUG OL ETI LSPS res nnn ac Poet ccc cece ceoncincsenaus cts tabs voseeccatuse cue ce tans Petes eee Coen PEG Haas Vasa Suva aEEU a on SEC auc duSe See STM tec bat de oT a dee eeuniee este aa 116 SAUETOTINIS TrrAVAdICa (REEGK U9OG) | sreeeree sce cea ce- cores ss ccucscescncag citar ects coe ictarcsecesscasesntocesicscescousenestesv oven sescmseseeviatenestsress 116 WSK CTIIGIOLCESIS Piece teterer tec ceed ctr et one aeanee eer Rete Tac eh gv rcs nas cai seth te te aeett re eectoncocreetceh teateen cee neehe nice te eee Deere Tete ses 118 Sijoeintamovi hy 1D ebro eta VorGler SOC Ney WON) crcconsocecdesdeecsses50-coctacceocosconodactoneeancoacgaodanodesasSsonAdoesGnoenedacooodacdonadoncrecoanceaccécno 118 Onniellacchaungzonensis\ (REECU9 OG) ereatc-ccectsrecceteecesceceec tree ee ee eee nee 118 SUWjosiicinilhy Chiierploo mio cen Wiimeaelll bz Sil nnelalerrti, MS) ooo cecececocuebeoscenoncacaseesonccoeccecoeeaceocacoacteconconner nooseeroceoccacconecenccsces 119 Inge ts: clitammb omit dye. scccses2ysesscescacescosdetesdospngieee es inv ate etait Su cents tog secu sensgsnvstantgssdcdetopts tosudess savdiesss descends tonssapuevsreesetonestess 119 SupenfamailysPlectamibonttoidear ones: 928 ee eysccrcccessccesscececseescerensure conte stestct vs cetavseeescencsaerecs oetocmncrentessnetencaentivennceeseenetees 120 Meptellinal(ieptellima) jminorispsnOns &. cocecacocecenté deceockecebeasccedeoncocond0 20 doncocconcobcocconacnc conte secacendepacdaccbonsage xd660>00505eeCondeacosonsaoronSndEnonsonSoA cone neeosobaceccroe 128 INCI ONMSCESTNSTUS..ccocconeeeccecresecosenccaccee maces cotphacocecechedicococeterénoio icon’ -ootossteoe Eco. aroendooesroconecodeodonccaSseé edcroccocosatonosecodcbsne eosconsacosecdos 128 IREITEIRETIEES nessoncsocnenicbocccoccoscodsoce de Oeecec een CELc oe Eco seas Lebt Rococo AnSO BD SOC EEOIOCEEEC Can od TaRRSSeaD 24300ocO0 COLO CO 0600550204 n ac noo canctnScoouepaaScEosOooGoRG 128 Appendix ........ copter nor Caco SEE CREE EEL CEE Croce EERE EERE TPCT re rector OSE CEPR oo SCR ERE OER CER CT 130 SYNOPSIS.. The brachiopod fauna from the Naungkangyi Group and its equivalents in the Shan States, Burma (Myanmar) is described and reviewed, partly from new collections and also from the publications of Reed in the early half of this century. It consists of 37 taxa within 31 genera, of which Dirafinesquina (Family Rafinesquinidae) is a new genus, and Dirafinesquina globosa and Leptellina (Leptellina) minor are new species. The fauna is of Late Ordovician (Caradoc) age. Affinity analysis between this fauna and other contemporary faunas from South China, North China, Kazakhstan, Altai, Wales, New South Wales and British Columbia shows that the Burmese fauna is most comparable with that from South China, and to a lesser extent North China, and very different from New South Wales and British Columbia. This indicates that the Shan-Thai (Sibumasu) palaeoplate, upon which the Shan States were situated during the Ordovician, was close to the South China palaeoplate. © The Natural History Museum, 1998 KXIGIAO ae) 110 INTRODUCTION During the early 1970s the then Institute of Geological Sciences of Great Britain (IGS) undertook field work on behalf of the United Nations in the Shan States, Burma (a country often now termed Myanmar) with the prime aim of establishing the nature and eco- nomic prospects of lead-zinc-silver mineralisation of the area. The rocks studied were Cambrian to Cretaceous in age, with substantial igneous intrusions, and included the Ordovician Naungkangyi Group and its equivalent rocks from which came the brachiopods described here. These were collected by the IGS survey teams, in particularly A. H. G. Mitchell and B. J. Amos, and sent to the Natural History Museum, London, for identification amongst other faunas. The results, including the preliminary identifications of the brachiopods by one of us (LRMC) were published in two memoirs and accompa- nying geological maps: Garson, Amos & Mitchell (1976) for parts of the Southern Shan States (AM and BA in Fig. 1) and Mitchell et al. (1977) for parts of the Northern Shan States (AM, TM andYA in Fig. 1). The Naungkangyi Group faunas had also been collected in the early years of the century by the Indian Geological Survey, summa- rised by La Touche (1913), and the brachiopods published in four papers by Reed (1906, 1915, 1932 and 1936); however, Reed described them somewhat in isolation from contemporary faunas in adjacent parts of Asia. The purpose of the present paper is to reidentify and partially redescribe the Naungkangyi brachiopods in the light of modern brachiopod studies, and to compare them with nearby areas, in particular South China. @ Wabyudaung a _ 7@Padaukpin MANDALAY 97 © 7 Maymyo [Ss Y SS ! CS Ass ( \ \ ; pERIEEO eccan / / 21cm, “MEIK Oa ) Sk @Pindaya 97° Fig. 1 the prefixes to the new fossil localities and collections described here. Gane / e@ Bawzaing L.R.M. COCKS AND ZHAN REN-BIN BRACHIOPOD FAUNA OF THE NAUNGKANGYI GROUP AND EQUIVALENTS There follows a list of the fauna which we recognise from the Naungkangyi Group and its equivalents. Those taxa with an asterisk (*) are recorded and figured by Reed (1906, 1915, 1932 and 1936) but were not recollected by the IGS team, and are included here only on the basis of our interpretation of Reed’s figures. Reed’s original attributions are given in square brackets. *Lingulella sp. [Lingula cf. quadrata: 1906: 49, pl. 4, fig. 1]. *Palaeoglossa? sp. [L. cf. attenuata: 1915: 8, pl. 2, fig. 5]. *Schizotreta sp. [Schizotreta cf. elliptica: 1906: 50, pl. 4, figs 2, 2a]. Plaesiomys taungtalensis (Reed, 1936) [Orthis (Dinorthis) flabellulum: 1906: 62, pl. 4, figs 4-6]. *Plaesiomys sp. [O. (Dinorthis) porcata birmanica: 1915: 10, pl. 2, figs 12-13]. *Glyptorthis sp. [O. (Glyptorthis) sp.: 1936: 25, pl. 1, fig. 24]. Nicolella sylvatica (Reed, 1936) [O. (Hesperorthis) cf. laurentina: 1936: 20, pl. 1, fig. 15; O. (Wattsella?) pontilis: 1936: 27, pl. 2, figs 5—7]. Nicolella sp. [O. (Nicolella) cf. actoniae: 1936: 29, pl. 2, fig. 9]. *N. sp. [O. (Plectorthis) cf. dichotoma: 1936: 20, pl. 1, fig. 23]. *N. liberalis (Reed, 1936) [O. (Eridorthis) liberalis: 1936: 22, pl. 1, figs 3, 3a, 4; O. (E.) kalavensis: 1936: 23, pl. 1, figs 1-2]. fo a | Mandalay! i \ - | 1 BURMA L-_ -__-14 Taunggyi _ _ ~ / -e A - - X- Location map of Shan States, Burma (Myanmar), with dotted blocks showing the main areas of IGS mapping, which include AM, BA, TM and YA, CARADOC BRACHIOPODS FROM THE SHAN STATES *Ptychopleurella sp. [O. (Ptychopleurella) cf. lapworthi: 1936: 27, pl. 2, fig. 4]. Saucrorthis irravadica (Reed, 1906) [Orthis pustulifera: 1936: 18, pl. 1, figs 7-14, pl. 2, fig. 3]. Skenidioides sp. [Skenidioides cf. billingsi: 1936: 68, pl. 2, figs 8, 8a]. *S. sp. [O. (Hesperorthis?) sp.: 1936: 20, pl. 1, fig. 19]. *Indet. draboviid [O. (Dalmanella) sinchaungensis: 1936: 28, pl. 2, figs 12—15a]. *Dalmanella? sp. [O. (D.) testudinaria shanensis: 1915: 9, pl. 2, figs 8, 11]. Onniella chaungzonensis (Reed, 1906) [O. (D.) testudinaria: 1906: 60, pl. 4, figs 25-26; O. (D.) testudinaria shanensis: 1915: 9, pl. 2, figs 6-7, 9-10]. *Indet. dalmanelloids [Yeosinella consignata: 1932: 193, pl. 3, figs 1 la, 2; 1936: 30, pl. 4, fig. 11]. Indet. clitambonitid. Leptellina (Leptellina) minor sp. nov. [Leptelloidea (?Leangella) cf. derfelensis: 1936: 43, pl. 4, figs 24-25; L. (Leangella) cf. sholeshookensis: 1936: 43, pl. 4, fig. 28]. *Indet leptellinids [Leptelloidea yeosinensis: 1932: 196, pl. 3, figs 3-6; L. campestris: 1936: 42, pl. 3, figs 16-17; Leptestina? sp.: 1936: 46, pl. 3, fig. 4]. *Leangella (Leangella) sp. [Plectambonites cf. llandeiloensis, Reed 1915: 13, pl. 3, fig. 3]. Bekkerella subcrateroides (Reed, 1906) [Rafinesquina (Bekkerella) gentilis: 1936: 38, pl. 4, fig. 14]. Ishimia subdeltoidea (Reed, 1906) [R. (Kjaerina) cf. felix: 1936: 37, pl. 4, fig. 1]. Ptychoglyptus? shanensis, Reed, 1932: 195, pl. 3, fig. 15. *Indet. sowerbyellids [Plectambonites repanda: 1906: 56, pl. 4, fig. 38; Sowerbyella cf. liliifera var. triangulum: 1936: 39, pl. 4, fig. 10]. *Indet. plectambonitoid [Plectambonites quinquecostata: 1906: 55, pl. 4, figs 34-35; P. sericea: 1906: 57, pl. 4, figs 36-37]. Bellimurina (Bellimurina?) sp. *Indet. strophomenids [Strophomena sp.: 1915: 12, pl. 3, fig. 1; Rafinesquina (Kjaerina) cf. praecursor: 1936: 71, pl. 3, fig. 18]. *Indet. furcitellinid [R. imbrex: 1906: 52, pl. 5, figs 9-12]. Dirafinesquina globosa gen. et sp. nov. [R. cf. alternata: 1936: 69, pl. 3, fig. 6; R. cf. semiglobosina: 1936: 70, pl. 3, fig. 7]. Indet. leptaenines [Leptaena cf. juvenilis: 1936: 33, pl. 3, fig. 3;L. cf. richmondensis: 1936: 34, pl. 3, fig. 11; L. spectata: 1936: 34, pl. 3, fig. 12]. Glyptomena sp. Indet. syntrophopsid. Porambonites spp. [P. intercedens: 1906: 68, pl. 5, figs 15, 15a, 15b; P. sinuatus: 1915: 14, pl. 3, figs 4-5; P. cf. acutiplicata: 1936: 48, pl. 3, figs 1-2; P. cf. wahli: 1936: 49, pl. 3, fig. 15; Clitambonites cf. squamata: 1906: 66, pl. 5, fig. 14; C. cf. ascendens: 1936: 31, pl. 3, fig. 14]. Protozyga? haydeni Reed, 1936: 51, pl. 4, fig. 12. *Cyclospira sp. Reed, 1936: 52, pl. 4, fig. 13 [?Hyattidina sp.: 1932: 206, pl. 3, figs 17, 18]. In addition, Reed figured the following which we find indetermi- nable, and have therefore omitted both from the above list and also from our faunal analysis of palaeobiogeography (not in this list are other determinations by Reed without any figures): Ahtiella? sp.: 1936: 47, pl. 1, fig. 20; Clitambonites cf. pyron: 1906: 65, pl. 5, figs 13, 13a; Chonetes? thebavensis sp. nov.: 1906: 57, pl. 5, fig. 16 (perhaps an orthoid); Gonambonites 111 (Antigonambonites ) emancipatus: 1936: 67, pl. 1, fig. 25; /ngria? sp.: 1936: 47, pl. 4, fig. 2; Leptaena? ledetensis sp. nov.: 1906: 54, pl. 4, figs 39-41 (perhaps a plectambonitoid); Leptelloidea cf. leptelloides: 1936: 73, pl. 4, fig. 9; L. (Leangella?) lamellata sp. nov.: 1936: 44, pl. 4, figs 22, 23, 23a (indeterminable plectambonitoid); Leptestia cf. musculosa: 1936: 45, pl. 3, fig. 8; Orthis calligramma var.: 1906: 59, pl. 4, fig. 3; 1915: 11, pl. 2, figs 14, 14a; O. (Dalmanella) elegantula: 1906: 60, pl. 4, figs 23— 24: O. (Hesperorthis) cf. tricenaria: 1936: 68, pl. 1, fig. 22; O. (Platystrophia) biforata var.?: 1915: 10, pl. 2, fig. 15; O. (Ptychopleurella) pinea sp. noy.: 1936: 26, pl. 1, figs 18, 18a (indeterminable orthoid); Petroria cf. rugosa: 1932: 98, pl. 3, fig. 16; Protozyga? cf. obsoleta: 1936: 52, pl. 5, figs. 9-10; Rafinesquina cf. jaervenis: 1936: 71, pl. 3, figs 13, 13a; R. (or Leptaena) cf. nubigena: 1936: 72, pl. 1, fig. 16;R. cf. richardsoni: 1936: 37, pl. 3, fig. 9; Skenidioides cf. billingsi: 1936: 68, pl. 2, figs 8, 8a, 16-17; S. cf. oelandicus: 1936: 30, pl. 2, figs 18-21; Sowerbyella ct. cylindrica: 1936: 40, pl. 4, fig. 15; S. cf. himalensis: 1936: 40, pl. 4, fig. 3; S. wilsoni sp. nov.: 1936: 41, pl. 4, figs 4-8 (indeterminable plectambonitoid); Stropheodonta aff. corrugatella: 1915: 12, pl. 3, figs 2, 2a; Strophomena cf. subtenta: 1936: 35, pl. 3, fig. 10; S. (Actinomena) cf. subarachnoidea: 1936: 36, pl. 3, fig. 5: Syntrophina cf. affinis: 1936: 49, pl. 1, fig. 17; Vellamo nemoralis: 1936: 31, pl. 1, figs 5—6; V. cf. ?simplex: NOBGRS2 5 ple lestion Ze AGE OF THE FAUNA From the above list, we perceive that the known fauna from the Naungkangyi Group and its equivalents consists of 31 genera, amongst which 32% are orthoids and 42% strophomenoids, and that these two groups are also the most abundant. The absence of rhynchonelloids 1s an outstanding character of the fauna. Besides the two endemic genera, Bekkerella and Dirafinesquina, most of the others are limited to the Ordovician, and mostly the Llandeilo to Ashgill. Plaesiomys is widely distributed and all its occurences are of Caradoc and Ashgill age, so is Nicolella, which is also found in the early Caradoc Shihtzupu Formation of South China. The Saucrorthis in our fauna is its first record outside South China, where it is reported only from the Shihtzupu Formation. Onniella is of Caradoc to Ashgill age with its acme in the Caradoc. Most of the known species of Protozyga are limited to the early to middle Caradoc of North America, north-west Europe and south-east Asia (Copper 1986: 834). Cyclospira ranged from the Caradoc to the Ashgill, and was particularly common in the late Caradoc (Copper 1986: 847). Ishimia is known from Llanvirn to early Caradoc rocks, Ptychoglyptus from the Caradoc to the Ashgill, Bellimurina only from the Caradoc andGlyptomena from the Llandeilo to the Caradoc. Once again, Leptellina (Leptellina), Leangella (Leangella), Bellimurina, Leptaena (Leptaena) and Glyptomena are also known in the Shihtzupu Formation of South China. Fortey & Cocks (1998) have also discussed the age of the Upper Naungkangyi Beds. Thus the faunas studied here from the Naungkangyi Group and its equiva- lents in the Shan States are probably of Caradoc age. At what period within the Caradoc these rocks were deposited is less certain. Any age above the early Caradoc would extend upwards the ranges of Saucrorthis and Ishimia. However, since the Naungkangyi Group is more than 2000m thick, then a variety of ages may be represented. However, in addition to the faunas discussed above, there are clearly also some earlier Ordovician brachiopods occurring in the Shan States. Reed (1932: 182, pl. 3, figs 7-14) described and figured 112 what he identified as the new species Orthis (Dalmanella) emancipata from Bawzaing, which he listed together with some unfigured molluscs, crinoids and the trilobite Ogygites cf. yunnanensis Reed. Later he listed and described a further fauna from the Namnoi Horizon, Southern Shan States (Reed 1936: 82), including the new brachiopod Orthis (Paurorthis) hehoensis together with trilobites such as undoubted Annamitella which Dr R. A. Fortey confirms is restricted to beds no younger than Llandeilo, and is more probably of Llanvirn age. Comparably, also from the Southern Shan States, the Natural History Museum possesses several blocks (BC 52144— 52153) from Twinzontaung, collected and presented by T. O. Morris in 1929. These contain hundreds of specimens, mostly external moulds of a monospecific although unidentified orthoid which again has an earlier Ordovician aspect. There is also the latest Ordovician (Hirnantian) fauna from the Panghsa-pyé Beds, originally described by Reed (1915) and revised by Cocks & Fortey (1997). Thus there are at least three Ordovician horizons present in the Shan States, (a) the Llanvirn-Llandeilo, (b) the Caradoc fauna described here, and (c) late Ashgill faunas from the Panghsa-pyé Beds. FAUNAL ASSOCIATIONS Much of the new Naungkangyi material comes from localities AM77 and AM78 north-west of Linwe in the Neyaungga-Ye-ngan area, Southern Shan States (Mitchell ert al. 1977) at longitude 96°33 'E and latitude 21°14'N. The material was collected by A.H.G. Mitchell as blocks, which were split up in the Natural History Museum by one of us (LRMC). Collection AM77 yielded 45 specimens, of which 20 (44.4%) were Saucrorthis irravadica, 7 (15.6%) were Leptellina (Leptellina) minor and one was Onniella chaungzonensis, the remainder were 7 varied bryozoans (15.6%), 9 crinoids (20%) and a single conulariid. Collection AM78 yielded 185 specimens of which 122 (65.9%) were Leptellina (Leptellina) minor, 23 (12.4%) were Dirafinesquina globosa and one each were Nicolella sylvatica, Glyptomena sp. and another unidentified orthoid, together with 21 (11.4%) crinoids, 5 (2.7%) the trilobite Nesewretus birmanicus, 3 (1.6%) various bryozoans, 5 (2.7%) gastropods of three different kinds, and one conulariid. Even though most of the brachiopods were disarticulated and formed part of a shell hash, the fact that 62 ventral valves and 60 dorsal valves of Leptellina (Leptellina) minor were counted in AM78 indicates, nevertheless, that the distance of transportation from the original life habitat to the area of final burial is unlikely to have been great. All the other material at our disposal were either small collections or single isolated museum specimens from a wide variety of locali- ties. Thus a proper assessment of the associations and hence communities of the Naungkangyi Group must await more substan- tial systematic collecting. However, even with the small amount of material available, it is clear that the brachiopod diversity of the Naungkangyi Group, although quite large when the Group is consid- ered as a whole, is nevertheless rather small when the individual localities and horizons are considered separately. This diversity is much less than, for example, in the neighbouring Shihtzupu Forma- tion in South China, from which individual beds have yielded over 20 different brachiopods from lithologies which are broadly similar to the Naungkangyi Group. The conclusions reached are that the Naungkangyi associations known to us probably colonized only the shallower parts of the contemporary Ordovician shelf and that the contemporary middle to deeper water faunas are either not preserved or have not yet been found. L.R.M. COCKS AND ZHAN REN-BIN PALAEOGEOGRAPHICAL ANALYSIS The Ordovician was a period of continental dispersal (Cocks & Fortey 1990) and southeast Asia has been recognized as consisting of a number of terranes, one of which is the Sibumasu (or Shan-Thai) terrane including much of the Malay Peninsula, West Thailand, Burma and western Indonesia. The Indochina terrane lies immedi- ately to the east of Sibumasu and the South China terrane to the northeast (Mitchell 1981, Burrett et al. 1990). The tectonic bounda- ries of the Sibumasu terrane are the Uttaradit-Nan to Raub-Bentong sutures to the east and the Shan boundary to the west (Bender 1983, Metcalfe 1992). The Shan States of Central to North Burma (Fig. 1) lie in the western part of the Sino-Burman Ranges. The Naungkangyi Group and its equivalents in the Shan States were deposited at the northern end of the Sibumasu palaeocontinent in the Late Ordovician. From the marine benthic shelly fossils found in these rocks, we can evaluate its relationships with other contemporary terranes. Table | shows the faunal affinity indices between eight Caradoc brachiopod faunas calculated by three different formulae as recommended by Rong et al. (1995) (for faunal lists see Appendix). 1. The Caradoc Naungkangyi fauna is closest to the early Caradoc Shihtzupu Formation fauna of South China (Xu ef al. 1974). During the later Caradoc, the purple-red Pagoda Limestone was deposited on the vast area of the Yangtze Platform with a deep- water Foliomena fauna quite different from the shallower-water (probably BA2 to BA3 according to Boucot’s (1975) concept of Benthic Assemblages) Naungkangyi fauna. There are many com- mon components between the Naungkangyi and Shihtzupu faunas: some genera (such as Saucrorthis) are only recorded from these two areas. This confirms that the South China and Sibumasu terranes were not far apart, a relationship which continued into the Ashgill (Cocks & Fortey 1997, Fortey & Cocks 1998). 2. The Naungkangyi fauna shares some similarity with the Caradoc fauna of the Bala District, Wales (Williams 1963), as is shown by the nine common genera, Lingulella, Nicolella, Skenidioides, Dalmanella, Onniella, Sowerbyella, Glyptomena, Bellimurina and Cyclospira. However, these nine genera are widespread or even cosmopolitan, and thus the data indicate only that the Naungkangyi fauna was faunally connected to many other areas in Caradoc times. 3. Also similar to the Naungkangyi fauna is the one from the late Caradoc Pingliang Formation of Shaanxi, North China (Fu 1982, Rong & Zhan 1996). This fauna overlies graptolitic shales and underlies the even shallower-water Beiguoshan Formation fauna of Ashgill age (Rong & Zhan 1996), and thus represents the transition between shallow and deep water faunas. The constitu- ents in common with the Naungkangyi fauna are Skenidioides, Leangella (Leangella), Sowerbyella and Bellimurina, but in addition there are some typical representatives of the deeper- water Foliomena fauna, including Foliomena itself. Since the Pingliang fauna has a comparatively high affinity index with the Shihtzupu fauna of South China, we can postulate that South China, North China and Sibumasu were close together during the Late Ordovician, with North China a little further away from the other two, and that the faunas on them were controlled by comparable environmental factors. 4. The Caradoc fauna from New South Wales, Australia (Percival 1991) has no common constituents with any of our listed contem- porary faunas apart from cosmopolitan genera such as Ptycho- pleurella, Skenidioides and Sowerbyella. This is also true of the mid Ashgill (Zhan & Cocks 1998), and indicates that Australia CARADOC BRACHIOPODS FROM THE SHAN STATES Table 1 113 Affinity indices between eight Caradoc brachiopod faunas. BUR, the present fauna; SCH, Guizhou, South China; NCH, Shaanxi, North China; KAZ, Chingiz, Kazakhstan; ALT, Gorny Altai, Russia; WAL, Bala, Wales; NSW, New South Wales, Australia; BCC, British Columbia, Canada (for stratigraphy and references see text). Three numbers are shown for each relationship following the different formulae discussed by Rong ef al. (1995) in the lower left part of the diagram and their averages in the upper diagonal. pf fe | poe | | NCH 0.3373 0.2557 SCH 1 was in poor faunal contact with South China and Sibumasu in the Late Ordovician, even though they were both parts of Gondwana. The Caradoc faunas from Kazakhstan and Altai are greatly different from the Naungkangyi fauna; a result which is in contrast with the findings of Zhan & Cocks (1998), which indicated that those two terranes were closely related faunally to the South China terrane in mid Ashgill time. 5. The comparatively deeper-water Bimuria fauna of North America described by Jin & Norford (1996) from the Advance Formation in the northern Rocky Mountains, British Columbia, has extremely low similarities with any other contemporary faunas compared here, which indicates that all the other seven sites were far away from Laurentia in Caradoc times. Thus this brachiopod faunal analysis supports Fortey & Cocks’ (1998) conclusions that during the Late Ordovician the Sibumasu terrane was closely related to South and North China, and that Sibumasu was closer to South China, in contrast with the latter’s closeness to North China in the Early Ordovician. SYSTEMATIC PALAEONTOLOGY The figured and cited specimens are deposited in the Natural History Museum, London (BB and BC) and the Sedgwick Museum, Cam- bridge (SMA). Dimensions (in mm) are L = length, W = width, L, = pve |e | om | om | oe 0.1842 0.0222 bieren 0.1726 0.0580 0.0165 ae 0.0800 0.1039 0.3156 0.0997 0.1138 0.1410 0.1064 0.1218 length of cardinalia or ventral muscle field, L, = distance of the anterior end of dorsal muscle field away from the umbo, W, = width of cardinalia or ventral muscle field, W, = width of dorsal muscle field, N = number of ribs, «< = angle between the socket ridges or brachiophores. Superfamily LINGULOIDEA Menke, 1828 Family LINGULIDAE Menke, 1828 Genus PALAEOGLOSSA Cockerell, 1911 Palaeoglossa? sp. 1915 —_ Lingula cf. attenuata Sowerby; Reed: 8, pl. 2, fig. 5. DISCUSSION. Lingula cf. attenuata was described by Reed (1915) from the Upper Naungkangyi Group (late Caradoc) of Man-ngai, Northern Shan States, and is tentatively attributed to the genus Palaeoglossa here, since Sowerby’s attenuata is now the type species of that genus (Cocks 1978). However, no original material from the Burmese Ordovician is available to us and we are hesitant to identify the species. In addition, Reed (1906: 49, pl. 4, fig. 1) also listed Lingula cf. quadrata Eichwald from the Naungkangyi Group of Palin, Northern Shan States. This latter might be reassigned to the oboloid Lingulella using the differ- ences between Lingula and Lingulella featured in Williams er al. (1965) and Holmer (1989). 114 Superfamily ORTHOIDEA Woodward, 1852 Family PLAESIOMYIDAE Schuchert, 1913 Subfamily PLAESIOMYINAE Schuchert, 1913 Genus PLAESIOMYS Hall & Clarke, 1892 Plaesiomys taungtalensis (Reed, 1936) Pl. 1, figs 1-5 1906 Orthis (Dinorthis) flabellulum Sowerby; Reed: 62, pl. 4, figs 4-6. 1936 Orthis (Glyptorthis) taungtalensis Reed: 24, pl. 2, figs 10, 10a, 11. MATERIAL AND LOCALITIES. One dorsal valve (external and inter- nal moulds) from Chaungzon, longitude 96°52'E, latitude 22°21'N; one dorsal external mould from Naungkangale; and two dorsal valves (external and internal moulds) from Pangmaklang (about 20 km northeast of Kunkaw, Locality YA 365, longitude 97°16'E, latitude 22°42'N); all from the Naungkangyi Group of the Northern Shan States. DISCUSSION. Plaesiomys and Dinorthis are both large orthoids with relatively small cardinalia and long and elevated sub-triangular to subpentagonal ventral muscle fields (Wright 1964), but the former has multibranching costellae and the latter has simple costae. All the present specimens have branching costellae and small but well- developed cardinalia (about one quarter shell length) with a highly projecting plate-like cardinal process which is limited to the vari- ably-developed notothyrial platform, and so they are included in the genus Plaesiomys, although no ventral valves are available. Reed (1906) described and illustrated three specimens from the Naungkangyi Group at Chaungzon as Sowerby’s speciesflabellulum under the subgenus Dinorthis, which are the same species as our material in ribbing and dorsal interior. However, the true flabellulum (Williams 1963: 363, pl. 3, figs 14) has simple costae which only exceptionally branch. Orthis (Glyptorthis) taungtalensis (Reed 1936) was named from the Naungkangyi Series of Taungtala, Southern Shan States, and has branching ornamentation, a very convex dorsal valve and small cardinalia limited to the notothyrial platform, which are all present in our material and typical of Plaesiomys. Orthis (Dinorthis) porcata birmanica (Reed 1915: 10, pl. 2, figs 12-13) is another species from the Upper Naungkangyi Group at Ta-Pangtawng of the Northern Shan States which should be reassigned to Plaesio- mys, but it differs from taungtalensis (including Reed’s specimens of ‘flabellulum’ ) in having amore circular shell, denser costellae and a more elongate and anteriorly bilobed ventral muscle field. The type species of Plaesiomys, Orthis subquadrata (Hall 1847: 126, pl. 32A, figs la—o) from the Richmondian (late Caradoc and early Ashgill) of Ohio, USA, differs from taungtalensis in having much denser costellae and a much stronger and larger crenulated myophore. Plaesiomys robusta and Plaesiomys multiplicata, both from the late Caradoc of Glyn Ceiriog, Wales (Bancroft 1945), are very similar to taungtalensis, but can be distinguished by their more rounded shell, denser costallae, and different shape of ven- PLATE 1 L.R.M. COCKS AND ZHAN REN-BIN tral muscle field. Plaesiomys porcata (M‘Coy), from the Portrane Limestone (Caradoc), Ireland (Wright 1964: 187, pl. 4, figs 1— 12), is different from taungtalensis in having an ‘isolated’ cardinal process (without any notothyrial platform). Family PRODUCTORTHIDAE Schuchert & Cooper, 1931 Subfamily PRODUCTORTHINAE Schuchert & Cooper, 1931 Genus NICOLELLA Reed, 1917 Nicolella sylvatica (Reed, 1936) Pl. 1, figs 6-10 1936 Orthis (Glossorthis) sylvatica Reed: 21, pl. 2, figs 1-2. 21936 Orthis (Hesperorthis) cf. laurentina Billings; Reed: 20, pl. ities 15: 21936 Orthis (Wattsella?) pontilis Reed: 27, pl. 2, figs 5—7. MATERIAL AND LOCALITY. Four ventral external, six internal, and two dorsal valves (internal and external moulds) from the Li-lu Formation (upper part of Naungkangyi Group) at Ta-Pangtawng (about 10 km east of Longtawkno, Locality YA454.1, longitude 96°23'E, latitude 22°58'N) in the Northern Shan States. DESCRIPTION. Exterior. Semicircular shell 4.5—9.1mm long and 6.8-11.5mm wide with the length/width ratio 0.66—0.79. Lateral profile ventri-biconvex, gently convex dorsal valve with a clear sulcus originating from the umbo. Maximum width along the hinge line which extends laterally, forming a small ear. Curved and small ventral interarea apsacline; narrow dorsal interarea anacline. Ante- rior commissure slightly sulcate. Orament of 15—19 simple costae occasionally with some branching in the postero-lateral parts. No median costa on dorsal valve but a pair of comparatively weaker costae appear beside the median groove. Closely-spaced concentric growth lines well-developed on some specimens on the anterior one- third of the shell and showing several typically productorthid imbrications. No exopunctae observed. Ventral interior. Strong triangular teeth supported by thin, short and subparallel dental plates. Small, elongately oval and weakly- impressed muscle field without any apparent anterior or antero-lateral bounding ridges; the adductor and diductor scars are not distinguish- able. Strong ribs on the surface of the shell, reflected on the internal surface of both valves in a series of corresponding deep and narrow radial grooves which include the muscle field; the intervals between grooves are almost three times as wide as the groove. No vascular markings seen. Dorsal interior. Small cardinalia about one-fifth shell length and width; strong cardinal process with a swollen myophore, separated from the brachiophores, occupying the whole notothyrial platform which is slightly elevated; brachiophores triangular at their bases, projecting highly anteriorly and ventrally at about 75° to one another; weak brachiophore supports extend medially and meet at the median ridge to form a low and wide ridge parallel to the hinge line. Poorly impressed muscle field with a low and wide myophragm extending to the anterior margin. Figs 1-5 Plaesiomys taungtalensis (Reed). 1, BC 52159, Kunkaw, Locality YA43, dorsal internal mould, x 2. 2, BB 37726, Pangmaklang, Locality YA365, latex cast of a dorsal internal mould showing the cardinalia, x 4. 3, SMA 3132, Chaungzon, latex cast of a partial dorsal external mould, x 2. 4a, 4b, SMA 3131, Chaungzon, dorsal internal mould and latex cast, x 2. 5, BB 37724, Pangmaklang, Locality YA365, dorsal internal mould, x 2.5. Figs 6-10 Nicolella sylvatica (Reed). 6-9, Ta-Pangtawng, Locality YA454.1. 6a—c, BB 37738, latex casts of ventral exterior and interior, and ventral internal mould, x 3. 7a, 7b, BB 37736, dorsal internal mould and latex cast, x 4. 8a—c, BB 37739, 8a, latex cast of dorsal exterior with a ventral exterior at the top right (BC 52414), x 4; 8b, 8c, latex cast and internal mould of dorsal interior, x 4. 9a, 9b, BC 52414, latex cast and internal mould of ventral interior, x 4. 10a, 10b, BB37682, Neyaungga, Locality BA490, latex cast and internal mould of ventral interior, x 4. Fig. 11 Saucrorthis irravadica (Reed). BB37705, Linwe, Locality AM77, latex cast and internal mould of ventral interior, x 4. 115 CARADOC BRACHIOPODS FROM THE SHAN STATES 116 MEASUREMENTS IL, W L/W Wil W1/W N BB37736, dorsal valve 6.0 - - 1.8 - 16 BB37737, ventral valve 5) 7.0 0.74 Il 0.30 15 BB37738, ventral valve 9.1 11.5 0.79 Zoi 0.27 19 BB37739, dorsal valve 4.5 6.8 0.66 1.3 0.19 16 BB37743, ventral valve 6.2 8.1 0.77 1.9 0.23 15 DISCUSSION. According to Williams’ (1963: 352) emended di- agnosis, Nicolella has a plano-convex shell, an ornament of simple costae with a very few rarely developed costellae, strong teeth supported by short receding dental plates, an elongately oval ventral muscle field without any bounding ridges, and small cardinalia with an elevated notothyrial platform. Both Reed’s (1936) illustrated specimen and our present material possess these main characters. The specimen identified by Reed (1936: 20, pl. 1, fig. 15) as Orthis (Hesperorthis) cf. laurentina Billings is a slightly distorted dorsal valve from the rocks corresponding to the Naungkangyi Group in the Southern Shan States of the same age as sylvatica. Its outline, ribbing and concentric growth lines are similar to sylvatica, but without interiors is only question- ably reassigned here to sylvatica. Although Orthis (Wattsella?) pontilis (Reed 1936: 27, pl. 2, figs 5—7) has a similar locality and horizon to sylvatica and the same exteriors as the latter, its large ventral muscle field and apparent dorsal muscle bounding ridges make us uncertain whether or not it is truly a junior synonym of sylvatica. The type species of Nicolella, Orthis actoniae J. de C. Sowerby, has been studied and discussed by several authors, such as Davidson (1868: 252, pl. 36, figs 5-17), Williams (1963: 353, pl. 1 figs 15-19, text-fig. 6) and Wright (1964: 165, pl. 2, figs 1-7, 10-11), all from Caradoc material. It differs from sylvatica in having more widely divergent brachiophores and in lacking the slight fold and sulcus. Nicolella delicata (Xu, Rong & Liu 1974: 151, pl. 66, figs 28-30), from the Shihtzupu Formation (early Caradoc) of Zunyi, Guizhou Province, South China, can be distinguished from sylvatica by having well-developed exopunctae and stronger dental plates en- closing a more circular ventral muscle than sylvatica and might even be attributable to Sulevorthis. O. (Eridorthis) liberalis (Reed 1936: 22, pl. 1, figs 3, 3a, 4) and O. (Eridorthis) kalavensis (Reed 1936: 23, pl. 1, figs 1-2) are two new species named by Reed on the basis of a ventral and a dorsal valve respectively. Because they are both from the rocks corresponding to the Naungkangyi Group at Taungtala of the Southern Shan States and have similar ribbing and shell sizes, we think they might be the same species and, if so, liberalis would be the senior synonym. It differs from sylvatica in having much coarser and branching ribs and a sessile pseudospondylium in the ventral inte- rior; however, with the minimal material available, its generic attribution is doubtful. PLATE 2 L.R.M. COCKS AND ZHAN REN-BIN Nicolella sp. 1936 Orthis (Nicolella) cf. actoniae Sowerby; Reed: 29, pl. 2, fig. 9. MATERIAL AND LOCALITIES. Two dorsal and one ventral external moulds from the Naungkangyi Group at Kunkaw; four dorsal and two ventral external moulds from the Naungkangyi Group at Chaungzon, both in the Northern Shan States; and one ventral external mould from the rocks corresponding to the Naungkangyi Group at Neyaungga in the Southern Shan States. DISCUSSION. Reed illustrated only exteriors, which makes further identification unreliable, although the external morphology is simi- lar to Nicolella actoniae J. de C. Sowerby from Shropshire. These Burmese specimens differ from N. sylvatica in having nearly flat dorsal valves and branching ribs (costellae) at two-thirds of their shell length. Genus SAUCRORTHIS Xu, Rong & Liu, 1974 Saucrorthis irravadica (Reed, 1906) figs 1-5 1906 Orthis irravadica Reed: 62, pl. 4, figs 15-22. 1915 Orthis irravadica Reed; Reed: 11. 21932 Yeosinella consignata Reed: 193, pl. 3, figs 1-2. 21936 Orthis pustulifera Reed: 18, pl. 1, figs 7-14; pl. 2, fig. 3. 1936 Yeosinella consignata Reed; Reed: 30, pl. 4, fig. 11. Pen ommles eI MATERIAL AND LOCALITIES. One dorsal internal and external, and one ventral external mould from the Naungkangyi Group at Namyun (about 7 km southeast of Longtawkno), Northern Shan States; eight ventral internal, nine external, five dorsal internal and eight external moulds at Linwe (Locality AM77), three ventral internal and exter- nal, and four dorsal internal and external moulds from the Neyaungga-Ye-ngan area (Locality BA490), both from the Kinle Siltstone Formation (equivalent to the Upper Naungkangyi Group) in the Southern Shan States. DESCRIPTION. Exterior. Small semicircular shell 2.4—6.6mm long, 3.3-9.1mm wide, with length/width ratio 0.70—0.88. Lateral profile ventribiconvex with dorsal valve gently convex or even flat with a median sulcus. Maximum width invariably along the hinge line. Ventral interarea comparatively large, apsacline, delthyrium open. Very small anacline dorsal interarea without chilidium, but most of the notothyrium is occupied by the cardinal process. Ornament of simple costae and fine concentric fila. Sharp costae generally unbranching, coarser anteriorly, 18 on the dorsal valve and 15 on the ventral valve irrespective of the shell size; no central costa on dorsal valve. In a well-preserved specimen (PI. 2, fig. 5), minute but distinct Figs 1-5 Saucrorthis irravadica (Reed). 1a, 1b, BB 37670, Neyaungga, Locality BA490, dorsal internal mould and latex cast, x 5. 2-5, Linwe, Locality AM77; 2, BB 37702, ventral internal mould, x 5; 3, BC 52411, latex cast of dorsal exterior, x 4; 4a—c, BB 37668, 4a, dorsal internal mould, x 5, and 4b, 4c, latex casts of dorsal exterior and interior, x 4; 5, BB 37695, dorsal external mould showing sparse exopunctae, x 12. Figs 6-10 Onniella chaungzonensis (Reed). 6, BB 37676, Neyaungga, Locality BA490, latex cast of ventral exterior, x 4. 7-10, Ta-Pangtawng, Locality YA454.1. 7a, 7b, BB 37731, latex cast of dorsal exterior, and dorsal internal mould, x 4. 8, BC 52412, ventral internal mould, x 8. 9, BC 52413, latex cast of dorsal exterior with ventral interarea, x 8. 10a, 10b, BC 52416, latex cast and internal mould of dorsal interior with a ventral valve (BC 52415) of Nicolella sylvatica (Reed), x 4. Figs 11-12 Indeterminate clitambonitid. Kunkaw. 11, BB 37777, Locality YA40.1, ventral internal mould, x 5. 12, BB 37771, Locality YA39, ventral internal mould, x 3. Figs 13-14 Leptellina (Leptellina) minor sp. noy. Linwe, Locality AM78. 13a, 13b, BB 37633, dorsal internal mould, and latex cast, x 4. 14a—c, BB 37643, ventral internal mould, latex cast and posterior view, x 5. CARADOC BRACHIOPODS FROM THE SHAN STATES 117 118 exopunctae are visible in lines along the rib crests, with a few additional exopunctae sporadically distributed on the rib slopes. Ventral interior. Small teeth supported by a pair of very short, subparallel dental plates. Poorly impressed muscle field about 28% as wide as the shell and open anteriorly. Strong crenulations along the peripheral area of both valves about one quarter of the shell length, which form broad, flat to weakly hollowed, scalloped ridges separated by narrow deep grooves. Dorsal interior. Cardinalia about one fourth as wide and one sixth as long as the shell; small cardinal process limited to the posterior part of the narrow but weakly elevated notothyrial platform, and connected with the posterior ends of the brachiophores on both sides. Well-developed brachiophores triangular at their base, highly projecting anteriorly and ventrally at 90—-110° to one another, and supported for their posterior one-third by thin subparallel plates. Weakly-impressed subquadrate muscle field just in front of the cardinalia, composed of two pairs of adductor scars on either side of a low and wide myophragm which becomes wider anteriorly to- wards the shell margin; the posterior scars always larger than the anterior pair. MEASUREMENTS IL, Ww L/W W BB37668, dorsal valve 47 5.5) 0.85 1.4 0.25 18 BB37669, dorsal valve 3.0 3.7 0.81 0.9 0.24 18 BB37670, dorsal valve 2.4 3.3 0.73 0.9 0.27 18 BB37682, ventral valve 4.5 6.4 0.70 1.8 0.28 15 BB37702, dorsal valve 47 5.8} 0.88 - - 18 BB37705, ventral valve 4.2 S32 0.81 1.5 B29665, dorsal valve 6.6 9.1 0.73 2.6 0.28 - DISCUSSION. The species irravadica was named by Reed (1906) within the genus Orthis for some small specimens from the Naungkangyi Group at several localities in the Northern Shan States. The illustrated exteriors and ventral interiors (Reed 1906: pl. 4, figs 15-22) are similar to our specimens from the same area and are assigned to Saucrorthis especially on the ribbing and cardinalia. Orthis pustulifera Reed (1936: 18, pl. 1, figs 7-14; pl. 2, fig. 3), from rocks corresponding to the Naungkangyi Group at Thitteikkon and Konleau, Southern Shan States, is much like irravadica in its external characters and cardinalia, but it has better-preserved exopunctae and stronger dorsal muscle bounding ridges and dental plates. The species is questionably included as a junior synonym of irravadica. The material identified by Reed (1932, 1936) as Yeosinella consignata Reed consists of some dorsal valves from rocks corre- sponding to the Naungkangyi Group at Ye-o-sin in the Southern Shan States which seem identical to our specimens of irravadica. No ventral valves of consignata are known, but should they also prove to be the same as irravadica, then Yeosinella would become a senior synonym of Saucrorthis. Saucrorthis, previously thought endemic to South China, is recorded here from outside it for the first time. The type species, S. minor (Xu, Rong & Liu 1974: 151, pl. 66, figs 1-4), from the Shihtzupu Formation (early Caradoc) at Zunyi, Guizhou Province, differs from irravadica in having a smaller subquadrate shell, nar- rower divergent brachiophores (about 75° as compared with 90-1 10° in irravadica), much stronger peripheral crenulations and more developed dental plates. Sulevorthis, a small orthid named by Jaanusson & Bassett (1993: 40) with its type species Orthis lyckholmiensis Wysogorski from the Lyckholm Beds (Vormsi Stage, late Caradoc) of K6rgessaare, Hiiumaa, Estonia, is very similar to Saucrorthis externally, but its strong cardinal process is elongate, occupies the entire notothyrial cavity and is separated from the brachiophores completely, and no notothyrial platform is developed. L.R.M. COCKS AND ZHAN REN-BIN Among all the species assigned to Sulevorthis by Jaanusson & Bassett (1993: 38), Orthambonites parvicrassicostatus (Cooper 1956: 309, pl. 35B, figs 11-25) from the Benbolt Formation (Porterfieldian, early Caradoc?) of Virginia, USA and Orthambonites humilidorsatus (Wright 1964: 160, pl. 1, figs 1-12) from the Portrane Limestone (Caradoc) of Ireland are the species of Sulevorthis most similar externally to our present material, particularly in the pres- ence of exopunctae. Family SKENIDIIDAE Kozlowski, 1929 Genus SKENIDIOIDES Schuchert & Cooper, 1931 Skenidioides sp. 21936 Skenidioides cf. billingsi Schuchert & Cooper; Reed: 68, pl. 2, figs 8, 8a. MATERIAL AND LOCALITY. One ventral valve (internal and exter- nal moulds), BB 37594, from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM 78), Southern Shan States. Discussion. A single broken shell 3.7mm long and 4.7mm wide, with radial costae branching only once within one-third of the shell length and 4 per mm on the shell anterior, a very high interarea and small teeth, is typical of Skenidioides. Reed described two species of this genus from the Southern Shan States, Skenidioides cf. oelandicus Wiman from the Naungkangyi Group at Nam Wabya (Reed 1936: 30, pl. 2, figs 18-21) and Skenidioides cf. billingsi Schuchert & Cooper from the Bawzaing Horizon (contemporary with the Naungkangyi Group) at Sinchaung (Reed 1936: 68, pl. 2, figs 8, 8a). S. cf. oelandicus does not appear from Reed’s illustrations to be a Skenidioides because the ventral interarea is far too small. S. cf. billingsi is represented in Reed’s material by a single ventral internal mould which may or may not be a Skenidioides and the same as the present specimen; it is poorly preserved. Superfamily DALMANELLOIDEA Schuchert, 1913 Family DALMANELLIDAE Schuchert, 1913 Subfamily DALMANELLINAE Schuchert, 1913 Genus ONNIELLA Bancroft, 1928 Pl. 2, figs 6-10 1906 = Orthis (Dalmanella?) chaungzonensis Reed: 61, pl. 4, figs Onniella chaungzonensis (Reed, 1906) 7-14. 1906 = Orthis (Dalmanella) testudinaria Reed: 60, pl. 4, figs 25— 26. 1915 = Orthis (Dalmanella) testudinaria shanensis Reed: 9, pl. 2, figs 6-7, 9-10. MATERIAL AND LOCALITIES. One dorsal and one ventral valve (both internal and external moulds) from the Naungkangyi Group in the Yadanatheingi area (Locality AM1); three dorsal valves (internal and external moulds), and five ventral internal and four external moulds from the Li-lu Formation (equivalent to the Upper Naungkangyi Group) at Ta-Pangtawng (about 10 km east of Longtawkno, Locality YA454.1), both in the Northern Shan States. One dorsal internal mould from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM77), Southern Shan States. CARADOC BRACHIOPODS FROM THE SHAN STATES DESCRIPTION. Exterior. Small transverse shell 2.4-5.4mm long and 2.7—-6.4mm wide with length/width ratio 0.75—0.89. Lateral profile unequally biconvex; gently convex dorsal valve with a con- spicuous sulcus originating from the umbo, much deeper ventral valve with strongest convexity along the hinge line. Maximum width near the shell midlength. Ventral beak small; slightly curved apsacline interarea; open delthyrium; narrow anacline dorsal interarea; with- out chilidium but notothyrium occupied by strong cardinal process lobes (Pl. 2, fig. 10a). Ornament of densely populated costellae, branching medially and laterally on dorsal valve and laterally on ventral valve three times: firstly at one-quarter shell length, secondly at one-third length and finally at two-thirds length. No median rib on dorsal valve, but a deep and narrow groove along the median line with a pair of weak costellae on both sides starting at one-quarter of the shell length. Concentric growth lines dense and even over the whole shell. One or two stronger growth lines common near the anterior margin. Endopunctate shell. Ventral interior. Strong teeth supported by a pair of subparallel, thick and short dental plates. Poorly impressed cordate muscle field about 30% of the length and width; slightly elevated central adductor scars not enclosed by diductor scars anteriorly. Strong crenulations near the margins of both valves about one-quarter of the length, which form broad, flat ridges separated by narrow deep grooves. Dorsal interior. Strong and erect cardinal process limited to the posterior part of the notothyrial cavity, well-developed myophore fissured centrally. Robust brachiophores triangular at their bases and highly projecting mainly ventrally and slightly anteriorly; short and slightly divergent stout fulcral plates variably developed (strong in Pl. 2, fig. 10). No apparent notothyrial platform, but weak elevation of notothyrial cavity often developed. Well impressed rectangular muscle field just in front of the cardinalia, extending to more than 60% of the length and about 40% of the width, with low and wide bounding ridges and myophragm; two pairs of adductor scars, with the anterior pair of scars larger than the posterior pair. Low and wide median ridge extending to the anterior margin. MEASUREMENTS IL, WwW L/W L, IU, WY, Ws BB37703, dorsal valve Sy) 5.8 0.89 0.9 - 13 - BB37731, dorsal valve 5.4 6.3 0.86 1.4 3.1 DO BS BB37736, ventral valve 2.4 Daj 89) 0.8 = 0.7 - BB37738, dorsal valve 4.8 6.4 0.75 1.0 3.4 IS) D7 DISCUSSION. Bancroft (1928: 55) established Onniella for small dalmanellids with a transverse shell, small beaks, dorsal sulcus and no ventral pallial markings. Later (Bancroft, 1945: 211), he further summarized the main and distinguishing characters of Onniella as a small dalmanellid with Resserella-like crural plates, unequal-sized dorsal muscle scars, feebly-developed ventral muscle field, and without apparent pallial markings.According toWilliams & Wright’s (1963) detailed revision, Dalmanella, externally somewhat close to Onniella, differs from the latter in having small fulcral plates, convergent brachiophore supports, comparatively smaller dorsal muscle scars and a more elongate ventral muscle field. Hurst (1979) has discussed and redefined the various species of Onniella from the type Caradoc area of Shropshire, including O. broeggeri Bancroft, the type species. According to his convincing discussion, the differ- entiation of species within Onniella should be on ribbing and some aspects of the interiors, especially the shape of the ventral muscle field, rather than only on their ribbing patterns as Bancroft believed. The present material from Burma lacks fulcral plates in most specimens, has slightly divergent brachiophore supports, the ventral adductor scars are not enclosed by diductor scars and has rectangular 119 dorsal muscle fields with larger anterior pair of scars; it is therefore assigned to Onniella. All the specimens identified as Orthis (Dalmanella?) chaungzonensis by Reed (1906: 61, pl. 4, figs 7-14) are from the Naungkangyi Group at Chaungzon, Northern Shan States, and have no essential differences from our material except for the equal-sized pairs of dorsal adductor scars shown in his figure 9, plate 4, which may have been overemphasised in Reed’s drawing. The two exteri- ors identified as Orthis (Dalmanella) testudinaria by Reed (1906: 60, pl. 4, figs 25-26), from the same locality and horizon as chaung- zonensis, have the same ribbing as the latter. Orthis (Dalmanella) testudinaria shanensis (Reed, 1915: 9, pl. 2, figs 6-11), from the Hwe Mawng Formation (equivalent to the Upper Naungkangyi Group) at Hkawnhkok, Northern Shan States, also has the same characters as chaungzonensis, except for two ventral interiors (Reed, 1915: pl. 2, figs 8, 11) which may be attributable to Dalmanella rather than Onniella, because the general shape of the ventral muscle field and the adductor and diductor scars are identical to that of the real D. testudinaria from the Baltic. The Orthis (Dalmanella) elegantula of Reed (1906: 60, pl. 4, figs 23-24) was based on two distorted specimens from the Naungkangyi Group at Taungkyun, Northern Shan States, and differs from chaungzonensis 1n shell outline, ribbing and cardinalia but cannot be identified with certainty here. Orthis (Dalmanella) sinchaungensis (Reed 1936: 28, pl. 2, figs 12-15a) was named from the rocks corresponding to the Naungkangyi Group at Taungbu, Southern Shan States, and can be distinguished from chaungzonensis by much denser costellae, different ribbing style and a larger dorsal muscle field consisting of two pairs of equal-sized adductor scars, and may be a draboviid. The type species of Onniella, O. broeggeri (Bancroft 1928: 56, pl. 2, figs 1-5) from the Onny Shale Formation of Shropshire, differs from chaungzonensis in having coarser costellae and a smaller dorsal muscle field. Superfamily CLITAMBONITOIDEA Winchell & Schuchert, 1893 Family CLITAMBONITIDAE Winchell & Schuchert, 1893 Indet. clitambonitid Pl. 2, figs 11-12 MATERIAL AND LOCALITY. Four ventral internal and two external moulds from the Naungkangyi Group at Kunkaw (Locality YA40) in the Kyaukme-Longtawkno area, Northern Shan States. DESCRIPTION. ‘Transverse elliptical shell 5.1-10.2mm long and 7.0-13.8mm wide with length/width ratio 0.73—0.92. Variably con- vex ventral valve with a shallow and narrow sulcus originating in front of the umbo; apsacline interarea with a large and open delthyrium. Maximum width along the straight hinge line or slightly in front of it. Ornament of multicostellae, 3-4 per mm near the anterior margin. Teeth small; short and shallow spondylium sup- ported by a weak median septum. DISCUSSION. One of the ventral internal moulds is clearly a clitambonitid, based on the spondylium supported by the short median septum, but it is uncertain whether or not a pseudodeltidium or chilidium is present and thus to which subfamily it should be attributed. The Clitambonites cf. squamata Pahlen recognised by Reed (1906: 66, pl. 5, fig. 14), from the Naungkangyi Group at Kunlein, Northern Shan States, and the Clitambonites cf. ascendens Pander identified by Reed (1936: 31, pl. 3, fig. 14), from rocks corresponding to the Naungkangyi Group at Nam Wabya, Southern Shan States, are both based on single specimens which are very 120 similar to each other, as Reed himself recognised, and can probably be reassigned to Porambonites (see below). The ventral exterior identified by Reed (1906: 65, pl. 5, figs 13, 13a) as Clitambonites cf. pyron (Eichwald), also from the Naungkangyi Group at Sedaw (about 15 km northwest of Kyaukme), Northern Shan States, cannot be revised here owing to lack of material; it may or may not be a clitambonitoid. Superfamily PLECTAMBONITOIDEA Jones, 1928 Family LEPTELLINIDAE Ulrich & Cooper, 1936 Subfamily LEPTELLININAE Ulrich & Cooper, 1936 Genus LEPTELLINA (LEPTELLINA) Ulrich & Cooper, 1936 Leptellina (Leptellina) minor sp. nov. Pl. 2, figs 13-14; Pl. 3, figs 1-5 1936 =Leptelloidea (Leangella?) cf. derfelensis Jones; Reed: 43, pl. 4, figs 24-25. 1936 =Leptelloidea (Leangella) cf. sholeshookensis Jones; Reed: 43, pl. 4, fig. 28. HOLOTYPE. BC 52418 (PI. 3, fig. 2), from the equivalent of the Upper Naungkangyi Group at Linwe (AM78), Southern Shan States, longitude 96°33’E, latitude 21°14'N. MATERIAL AND LOCALITIES. 107 specimens: 10 dorsal valves, 23 dorsal internal and 14 external moulds, four ventral valves, 33 ventral internal and 13 external moulds from the equivalents of the Upper Naungkangyi Group at Linwe (Localities AM77, AM78); moulds of two ventral interiors and one ventral exterior and counter- part interior from the Bryozoan Sandstone Formation (equivalent to the Upper Naungkangyi Group) in the Neyaungga-Ye-ngan area (Localities BA479, BA490); both in the Southern Shan States. Four ventral internal and two external moulds from the Li-lu Formation (equivalent to the Upper Naungkangyi Group) at Ta-Pangtawng (about 10 km east of Longtawkno, Locality YA454.1), Northern Shan States. DESCRIPTION. Exterior. Small semicircular shell 3.0—6.3mm long and 3.4-8.4mm wide, with length/width ratio 0.66—0.88. Lateral profile strongly concavo-convex, dorsal valve often dorsally genicu- late at about 60% of length, strongly convex ventral valve particularly medially. Cardinal extremities acute to nearly rectangular; max1- mum width along the hinge line. Large, flat and apsacline ventral interarea; posterior half of the delthyrium covered by well-devel- oped arched pseudodeltidium (PI. 3, fig. 1a). Smaller anacline dorsal interarea; open notothyrium mostly occupied by cardinal process lobes. Parvicostellate ornamentat with 4—5 finer costellae between each pair of coarser ones. No growth lines observed. Ventral interior. Small teeth with variably developed dental plates weak or absent and extending first subparallel and then medially to PLATE 3 L.R.M. COCKS AND ZHAN REN-BIN enclose the muscle field. Delthyrial cavity very deep. Rectangular or transversely elliptical muscle field elevated from the shell floor, 17— 27% of the length and 21-34% of the width; triangular median adductor scars often more elevated than the lateral diductor scars. Vascular markings lemniscate; a pair of strong vascular media originate from the antero-lateral ends of muscle field, extending forward subparallel and branching at about two-thirds of the length; a pair of very weak vascular spondylaria originate laterally from the muscle field, extending to the shell lateral margin with few branches. Dorsal interior. Small transverse cardinalia 16-21% of the length and 28-31% of the width; strong median cardinal process lobe projecting posteriorly and ventrally and continuous with the low and wide myophragm anteriorly; small lateral pair of lobes variably developed, sometimes absent; socket ridges connected with cardinal process medially and extending laterally subparallel to the hinge line, with two strong ventrally projecting lateral ends; sockets transverse and elliptical. Poorly-impressed circular muscle field just in front of the cardinalia, antero-medial pair of adductor scars slightly larger than the lateral pair. Thin median septum starting from the posterior end of the inner adductor scars, becoming higher anteriorly and reaching its acme at the junction with the platform at the strongest valve convexity. Weakly-elevated platform composed of a series of continual or continuous tubercles, not connected with hinge line posteriorly. Lemniscate vascular markings with a pair of vascular media originating from the anterior ends of inner adductor scars. MEASUREMENTS 1 Ww L/W IL. Nt NY NICINE BB37590, dorsal valve 5.2 7.8 0.67 OS 22 “OR BB37625, dorsal valve 5.6 7.5 0.75 OO On 21 0.28 BB37635, ventral valve 4.6 6.1 0.75 2 10!2.6) 2a 0.34 BB37647, dorsal valve 4.4 5.8 0.76 0.8 O18 1.8 0.31 BB37652, ventral valve 4.0 6.1 0.66 OI) 0235 ES) 0.25 BB37742, ventral valve 3.0 3.4 0.88 O35) ONT ON: 0.24 BB37755, ventral valve 6.3 84 0.75 iP Op Ms 0.21 DISCUSSION. This species is the most abundant component of our fauna. Reed (1936: 43) identified a probably identical ventral inte- rior as Leptelloidea (Leangella) cf. sholeshookensis Jones from rocks corresponding to the Naungkangyi Group at Taunggyi in the Southern Shan States. The true Leptelloidea sholeshookensis (Jones 1928: 488, pl. 15, fig. 19) has an undercut cardinal process and well- developed bema and platform, and has been reassigned to Leangella (Leangella) by Cocks & Rong (1989: 116). Reed also identified other specimens as Leptelloidea (Leangella?) cf. derfelensis Jones, but again that Welsh species has been reassigned to Leangella (Leptestiina) by Cocks & Rong (1989: 116). Reed illustrated no dorsal valves. Thus, with our more complete material than Reed, we can erect the new species minor, which we assign to Leptellina (Leptellina). \t differs from the type species L. tennesseensis (named by Ulrich & Cooper in 1936: 626, but illustrated by Ulrich & Cooper in 1938: 192, pl. 39, figs 1-2, 4-5), from the Lenoir Formation Figs 1-5 Leptellina (Leptellina) minor sp. nov. 1-4, Linwe, Locality AM78. la, 1b, BB 37623, latex cast and internal mould of ventral interior showing poorly developed pseudodeltidium and small teeth, x 5. 2a, 2b, BC 52418, Holotype, latex cast and internal mould of dorsal interior with another dorsal interior at the top left (BB 37590), x 5. 3, BB37659, dorsal internal mould, x 4. 4, BB 37629, latex cast of dorsal exterior, showing dorsal interarea and chilidium, x 4. 5, BC 52417, Ta-Pangtawng, Locality YA454.1, ventral internal mould, x 6. Figs 6-9 Bekkerella subcrateroides (Reed). 6-8, Kunkaw. 6, BB 37768, Locality YA50.1, latex cast of dorsal exterior, x 4. 7a—d, BB 37759, Locality YA256, latex cast of exterior, internal mould, latex cast of interior and posterior view of internal mould of ventral valve together with a dorsal external mould (BC 52410), x 4. 8a, 8b, BB 37774, Locality YA315.1, dorsal internal mould, and latex cast, x 3. 9a, 9b, BB 37750, Namyun, latex cast and internal mould of dorsal interior, x 2. Fig. 10 Ishimia subdeltoidea (Reed). B 29672, Tawmawgon, latex cast and internal mould of dorsal interior, x 2. CARADOC BRACHIOPODS FROM THE SHAN STATES 122 (Llandeilo) at Friendsville inTennessee, U.S. A., in having a smaller shell, less numerous parvicostellae and less acute cardinal extremi- ties. The Leptellina sinensis of Xu, Rong & Liu (1974: 152, pl. 66, figs 13, 17-18) from the Shihtzupu Formation (early Caradoc) of Guizhou, South China, differs from minor in having a much larger shell, comparatively larger dorsal interarea, denser parvicostellae, less well-developed ventral muscle field and dorsal platform. The specimen identified by Reed (1915: 13, pl. 3, fig. 3) as Plectambonites cf. llandeiloensis (Davidson) from the Li-lu Forma- tion (equivalent to the Upper Naungkangyi Group) at Li-lu, Northern Shan States, has an undercut cardinal process, strongly elevated bema and well-developed platform, and is here reassigned to Leangella (Leangella) sp. Davidson’s Ilandeiloensis itself has been reassigned to Leptellina by Williams (1962: 164). A ventral valve, the holotype of Reed’s new species Leptelloidea (Leangella?) lamellata (1936: 44, pl. 4, figs 22—23, 23a), from rocks correspond- ing to the Naungkangyi Group at Taunggyi of the Southern Shan States, is similar to L. (L.) minor in shell outline and convexity, but differs from the latter in having fewer larger costellae, a more deeply impressed and more elongate muscle field and a pair of strong vascular dentalia. Since only a single ventral valve was illustrated, we consider /amellata as generically indeterminable. Comparably, Leptelloidea yeosinensis was described from Ye-o-sin, Southern Shan States, by Reed (1932: 196, pl. 3, figs 3-6) and the well- illustrated dorsal valves indicate that it is a leptellinid, but differing from L. (L.) minor in its lack of thin dorsal median septum anteriorly and the presence of a bema. However, its detailed generic position is not determinable. Several variations are observed in our specimens of L. (L.) minor, including: (1) ventral convexity; most of the ventral valves are very convex but some are more gentle; (2) geniculation; over 80% of the dorsal valves have marked geniculation, while the remaining minor- ity have much weaker or even absent geniculation; (3) ventral muscle field; the dental plates are usually weak and enclose the elevated muscle field in which the medial adductor scars are higher than the lateral diductor scars. Sometimes the small teeth have no supports and the slightly elevated diductor and adductor scars are indistinguishable from each other; (4) cardinal process; the central lobe is always well-developed, while the lateral lobes are often absent; (5) platform; the presence of a platform is one of the main characters of this genus, but it is variably developed and elevated in L. (L.) minor, and occasionally itis even composed merely of a series of discontinuous tubercles. Genus BEKKERELLA Reed, 1936 Bekkerella subcrateroides (Reed, 1906) Pl. 3, figs 6-9 1906 Orthis subcrateroides Reed: 63, pl. 4, figs 27-33. 1915 Orthis subcrateroides Reed; Reed: 12. 1936 Rafinesquina (Bekkerella) gentilis Reed: 38, pl. 4, fig. 14. MATERIAL AND LOCALITIES. Nine dorsal internal, eight external, 10 ventral internal and four external moulds from the Naungkangyi Group at Kunkaw (Localities YA42, YASO.1, YA256 and YA315.1):; one dorsal internal, two external and four ventral external moulds from the Li-lu Formation (equivalent to the Upper Naungkangyi Group) at Li-lu (about 11 km southeast of Longtawkno, Locality YA630); one ventral valve (internal and external moulds) from the Taungkyun Formation (equivalent to the Lower Naungkangyi Group) at Li-lu (Locality YA139); one ventral internal mould at Chaungzon, and two dorsal internal moulds at Namyun, both from the Naungkangyi Group; all in the Northern Shan States. L.R.M. COCKS AND ZHAN REN-BIN DESCRIPTION. Exterior. Subquadrate to subcircular shell 6.9— 18.7mm long and 7.7—23.8mm wide with length/width ratio 0.7 1—1.0. Lateral profile concavo-convex; dorsal valve slightly concave medio- posteriorly with a small anterior geniculation; strongly convex ventral valve particularly medially. Cardinal extremities round, maximum width at about mid-length. Large flat apsacline ventral interarea, small beak, only posterior one-third covered by small arched pseudodeltidium; smaller hypercline dorsal interarea, notothyrium completely occupied by cardinal process. Multibranching costellae, equal in size, near the anterior margin, about 4 per mm. Growth lines closely spaced, 12 per mm longitudi- nally. Ventral interior. Stout triangular teeth without supports. Delthyrial cavity with some secondary shell accumulation. Poorly-impressed muscle field about one-third to two-fifths of shell length and width, without apparent surrounding ridges, adductor and diductor scars indistinguishable from each other. Variably-developed subperipheral ridge extending posteriorly towards the hinge line and then medially to the teeth lateral sides parallel to the hinge line. Vascular markings saccate, a pair of vascular media originating in front of the muscle field and extending forward with several branches. Dorsal interior. Small cardinalia 12-23% valve length and 21— 32% valve width; cardinal process usually simple but occasionally trifid, median lobe elongate and strongly projecting ventrally and posteriorly; thick and straight socket ridges divergent at 60—100°, extending posteriorly and connecting with the lateral lobes of cardi- nal process; the whole notothyrial cavity highly elevated and thickened by secondary shell; large deep sockets open antero- laterally. Slightly elevated quadrate muscle field with distinctive bounding ridges, posterior pair of scars a little larger than the anterior pair; thick and strong myophragm originating from the notothyrial platform, becoming thinner and higher anteriorly, with its acme just in front of the muscle field, merging into the platform. Variably-developed quadrate platform slightly undercut and extend- ing posteriorly to the hinge line. All the area outside the platform geniculate dorsally. MEASUREMENTS IL, W L/W LI LI/L W1 WI/W x BC52182, dorsal valve C19) TA OSO RIS ONO 2 AO ees oe BB37750, dorsal valve LS) WO “Ohl 245 OA) 24 O22 oP BB37757, dorsal valve le7/ PBS Os) 2} OI SO) Cyril — shay? BB37759, ventral valve hf eh 10) 29 O28 BS O33 - BB37774, dorsal valve 8:6) 104: 10:83) 16) OMS S39 082) 89° SMA3128, ventral valve 11.9 12.3 0.97 5.2 0.44 5.0 0.41 - Discussion. Bekkerella appears endemic to Burma and is charac- terized by undifferentiated fine radial ornamentation, a slightly elevated and distinctive dorsal muscle field, a strong median septum and a quadrate platform. Acculina and Shlyginia, also common in Caradoc times, are similar to Bekkerella in dorsal interior, but they both have parvicostellate ornamentation, and in addition Acculina has a resupinate profile, well-developed pseudodeltidium and a bilobed ventral muscle field with extended dental plates as bounding ridges (Cocks & Rong 1989: 103). Shlyginia has a much larger ventral muscle field within which adductor scars are enclosed by diductor scars, and a small cardinal process seldom projecting posterior to the hinge line. Reed (1936: 38) erected the subgenus Bekkerella within Rafinesquina, with Orthis subcrateroides Reed (1906) from the Naungkangyi Group at Chaungzon in the Northern Shan States as its type species. The single ventral interior which he illustrated from the Southern Shan States in 1936 has a muscle field which was overem- phasised in the drawing (Reed 1936, pl. 4, fig. 14), since none of CARADOC BRACHIOPODS FROM THE SHAN STATES Reed’s illustrated ventral valve muscle fields of subcrateroides is so elongate and divergent. All our present specimens are also from the Naungkangyi Group from several localities in the Northern Shan States and are identical to subcrateroides. Some variations observed in this material are: (1) dorsal concavity; most dorsal valves are slightly concave or nearly flat medial-posteriorly, with a small but strong geniculation anterior to the platform, but there are a few individuals with an evenly concave dorsal valve and no geniculation (e.g. Pl. 3, fig. 6); (2) cardinal process; lateral lobes are usually absent, but they are present in a few specimens and continuous antero-laterally with the straight socket ridges; (3) platform; most dorsal valves have a well-developed and slightly undercut platform, but a few specimens, particularly juveniles, have a very weak platform. Subfamily PALAEOSTROPHOMENINAE Cocks & Rong, 1989 Genus [SHIMIA Nikitin, 1974 Ishimia subdeltoidea (Reed, 1906) Pl. 3, fig. 10; Pl. 4, figs 1-7 1906 Rafinesquina subdeltoidea Reed: 52—53, pl. 5, figs 1-8. 1936 Rafinesquina (Kjaerina) cf. felix Reed; Reed: 37, pl. 4, fig. 1. MATERIAL AND LOCALITIES. Eight dorsal internal, six external, eight ventral internal and three external moulds at Tawmawgon (about 30 km north of Kyaukme); three dorsal internal, one ventral internal and one external moulds at Kunkaw (Localities YA45.1, YA315), both from the Naungkangyi Group; two dorsal internal and external moulds from the Li-lu Formation (equivalent to the Upper Naungkangyi Group) at Ta-Pangtawng (about 10 km east of Longtawkno); all in the Northern Shan States. Two dorsal internal moulds from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM77), Southern Shan States. TYPES. Lectotype, here selected, the original of Reed 1906, pl. 5, fig. 4, a dorsal internal mould from Tawmawgon, Northern Shan States. Indian Geological Survey Museum, Calcutta. DESCRIPTION. Exterior. Lateral profile concavo-convex; dorsal valve flat or slightly concave medial-posteriorly, with variably developed dorsal geniculation, some strong and nearly perpendicu- lar; ventral valve convex, with convexity increasing anterior to the dorsal valve geniculation. Cardinal extremities usually acute, maxi- mum width along the hinge line. Large, apsacline, flat ventral interarea; ventral beak slightly curved; delthyrium only about one- quarter covered by pseudodeltidium. Smaller hypercline dorsal interarea with a well-developed arched chilidium. Ornament of coarse parvicostellae, unevenly distributed, about 3-4 per mm near the margin; only 1-2 finer costellae between two coarser ones. Growth lines well-preserved on the geniculation, 8-9 per mm; several concentric comae often present postero-laterally. Ventral interior. Small triangular or wedge-like teeth without supports. Weakly-impressed muscle field with no bounding ridges; antero-median pair of diductor scars much larger than the postero- lateral pair and with a short and weak myophragm, small adductor scars in the posterior centre of the muscle field. Vascular markings leminiscate; vascular media originating from the inner sides of the anterior end of the muscle field, and vascular myaria starting between the two pairs of diductor scars. Dorsal interior. Cardinalia about one-fourth shell length and width; very high, thin plate-like cardinal process median lobe pro- 3) jecting ventrally, lateral lobes often absent; straight socket ridges separated from the median lobe, divergent at about 75—100°, extend- ing antero-laterally far beyond the sockets, showing thin plate-like crura; the cardinal area elevated by the deposition of secondary shell; deep and narrow or round sockets open or with thick and low bounding ridges antero-laterally. Well-impressed elongate oval mus- cle field including a smaller anterior pair and larger posterior pair of adductor scars, low bounding ridges often absent; thick and high myophragm originating from the notothyrial platform and extending forward to become thinner and higher, reaching its acme at the anterior end of the muscle field and continuous anteriorly with the thin median septum which ends before or merges into the platform. Quadrate platform slightly elevated, extending posteriorly to the hinge line. The geniculation is immediately anterior of the platform. Discussion. Most of our present material was collected from Reed’s type locality of suwbdeltoidea, Tawmawgon in the Northern Shan States, and is identical to Reed’s illustrated specimens. The distorted dorsal interior, from rocks corresponding to the Naungkangyi Group at Hpongyi Kyaung in the Southern Shan States and identified by Reed as Rafinesquina (Kjaerina) cf. felix, is basically similar to some of our specimens and is thus assigned to subdeltoidea here. The true felix of Reed (1917) is a quite different strophomenoid from the middle Ashgill of Girvan, Scotland (Cocks 1978). When Nikitin (1974: 59) established/shimia from the Middle Ordovician of Central Kazakhstan, he recognised four species, /. humilis (Nikitin 1974: 63; pl. 6, figs 1-3), from the Yerkebidaik Horizon (middle Caradoc) of Chingiz in Central Kazakhstan, lacks geniculation, but otherwise is the most similar to suwbdeltoidea, although it differs in having finer costellae and a more elongate bilobed ventral muscle field. The type species, /. ishimensis (Nikitin 1974: 61, pl. 5, figs 10-16) from the Karakan Horizon (late Llanvirn) of Kupriyanovka in Central Kazakhstan, can be distinguished in having finer and more differenti- ated costellae, larger ventral adductor scars, and stronger dorsal bounding ridges, median septum and platform. Some variations within the dorsal interior observed from our material of I. subdeltoidea are: (1) cardinal process; most specimens have only a strong single cardinal process lobe, but a few develop a pair of small lateral lobes, making the cardinal process trifid and hence the genus is appropriately placed within the Leptellinidae; (2) sockets; the antero-lateral sides are sometimes open, while a few specimens have low bounding ridges; (3) median septum; this usually ends before the platform, but in a few specimens it merges anteriorly with the platform. Family SOWERBYELLIDAE Opik, 1930 Subfamily PTYCHOGLYPTINAE Cooper, 1956 Genus PTYCHOGLYPTUS Willard, 1928 Ptychoglyptus? shanensis Reed, 1932 1932 Ptychoglyptus shanensis Reed: 195, pl. 3, fig. 15. 1936 Ptychoglyptus shanensis Reed; Reed: 37. DISCUSSION. Reed (1932) named the species Ptychoglyptus shanensis from rocks corresponding to the Naungkangyi Group at Ye-o-sin in the Southern Shan States, on the basis of a single specimen showing distinctive zigzag rugae interrupted by costae. Although it may be a Prychoglyptus, this is not certain until interiors are discovered, since very similar ornament can be found on some strophomenoid rafinesquinds such as Pentlandina. Thus the generic attribution is queried here. L.R.M. COCKS AND ZHAN REN-BIN 124 3 gs RGM b 11 9c 9b CARADOC BRACHIOPODS FROM THE SHAN STATES Superfamily STROPHOMENOIDEA King, 1846 Family STROPHOMENIDAE King, 1846 Subfamily FURCITELLINAE Williams, in Williams et al., 1965 Genus BELLIMURINA (BELLIMURINA) Cooper, 1956 Bellimurina (Bellimurina)? sp. Pl. 4, fig. 8 DISCUSSION. One ventral valve (internal and external moulds, BB37585) from the equivalents of the Upper Naungkangyi Group at Linwe, Southern Shan States, has some characters typical of Bellimurina (Bellimurina), such as a convex ventral valve with dorsal geniculation, a surface covered by zigzag rugae, and short and divergent dental plates (Cooper 1956: 854); but lack of material, especially dorsal valves, still makes our identification uncertain. Bellimurina rudis Xu, Rong & Liu (1974: 153, pl. 66, figs 14-16), from the Shihtzupu Formation (early Caradoc) of northern Guizhou, South China, is larger in shell size, has much stronger zigzag rugae and more impressed ventral muscle field with distinctive surround- ing ridges. It is therefore not conspecific with this Burmese specimen. Family RAFINESQUINIDAE Schuchert, 1893 Subfamily RAFINESQUININAE Schuchert, 1893 Genus DIRAFINESQUINA gen. nov. TYPE SPECIES. Dirafinesquina globosa sp. nov. DIAGNOSIS. Family characteristics of Rafinesquinidae. Like Rafinesquina but with ventral valve bounding ridges surrounding a suboval muscle field; cardinal process lobes weaker and erect rather than anteriorly directed and with socket ridges better developed. DESCRIPTION. As for Dirafinesquina globosa below. DISCUSSION. The true Rafinesquina, from the Caradoc-Ashgill of North America, has been revised and reillustrated by Rong & Cocks (1994). Reed (1906, 1936) attributed various Burmese specimens to species of Rafinesquina (see specific discussion below), but we consider that all the specimens in our collections and some of Reed’s material from the Shan States may be grouped together within a single species, erected below as Dirafinesquina globosa. The new genus can be firmly placed within the subfamily Rafinesquininae and the family Rafinesquinidae by its cardinalia, normal convexity and lack of rugae. There are ten other members of the subfamily. Of those of comparable age, Rafinesquina itself appears the closest, but with the differences mentioned in the diagnosis above. Dirafinesquina differs from Colaptomena and Hedstroemina in the large chilidium and pseudodeltidium and from the former in the lack of dorsal median septum; and from the latter in the lack of strong dental plates. It differs from Kjaerina in the suboval rather than triangular ventral muscle field and larger PLATE 4 125 chilidium, and from Kjerulfina in its lack of ventral geniculation and rugae. Megamyonia has distinctive ventral trans-muscle septa and other very different characters. Odoratus has ventral geniculation and lacks ventral muscle bounding ridges. Rhipidomena is resupi- nate and has dorsal trans-muscle ridges. Dirafinesquina globosa sp. nov. Pl. 4, figs 9-11; Pl. 5, figs 1-3, 5 21936 Rafinesquina cf. alternata Conrad; Reed: 69, pl. 3, fig. 6. 1936 Rafinesquina cf. semiglobosina Davidson; Reed: 70, pl. 3, mgs Wo HOLOTYPE. BB37593 (PI. 4, fig. 11), from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM78), Southern Shan States, longitude 96°33'E, latitude 21°14'N. MATERIAL AND LOCALITIES. 31 specimens: three dorsal internal and two external, 20 ventral internal and six external moulds from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM78) and Loke-pyin (about 14 km southeast of Ye-ngan, Locality AM106), Southern Shan States. DESCRIPTION. Exterior. Large, subcircular shell more than 20mm long and wide with length/width ratio about 1.0. Lateral profile concavo-convex; dorsal valve evenly and gently concave; ventral valve gently convex posteriorly, with variable but sometimes sharply increasing convexity dorsally at about mid-length. Cardinal ex- tremities round or rectangular, maximum width along the hinge line or a little anterior to it. Large flat apsacline ventral interarea with an arched pseudodeltidium, narrower anacline dorsal interarea with a much larger and more arched chilidium. Ornament of multibranching parvicostellae, 3-5 finer costellae between two coarser ones. No growth lines observed. Ventral interior. Small rod-like or triangular teeth supported by weak dental plates which extend forward as muscle bounding ridges. Well-impressed, elongated oval muscle field 43-55% valve length and 37-39% valve width; a pair of long, kidney-shaped adductor scars slightly elevated and open anteriorly; diductor scars narrowing anteriorly, but longer than the adductor scars. Saccate vascular markings with a pair of vascular media originating from the anterior ends of adductor scars. Dorsal interior. Relatively small cardinalia (Type B of Rong & Cocks 1994) with a variably developed, sometimes ponderous, cardinal process; triangular, sessile and discrete lobes including a plate-like shaft and a swollen myophore, and project ventrally and anteriorly; low, short, straight and variably thick socket ridges separated from the cardinal process; notothyrial cavity elevated; small shallow sockets open antero-laterally. Well-impressed circular muscle field, particularly posteriorly; low and wide myophragm starting from the notothyrial platform and narrowing anteriorly. No vascular markings observed. MEASUREMENTS. Most of our specimens are broken and so only Figs 1-7 Ishimia subdeltoidea (Reed). Tawmawgon. 1, BC 52420, ventral internal mould, x 1.5. 2, SMA 3124, latex cast of ventral exterior, x 1.5. 3a, 3b, SMA 3127, latex cast and internal mould of dorsal interior, x 1.5. 4, SMA 3126, dorsal internal mould, x 2. 5, SMA 3125, dorsal external mould, oblique view showing the dorsal geniculation, x 1.5. 6, BC 52191, dorsal internal mould showing small curved socket ridges, x 2. 7Ja—c, B 29664, latex cast and internal mould of a dorsal valve with another dorsal internal mould to the right, both with weaker platforms, x 1.5. Fig. 8 Bellimurina (Bellimurina)? sp. BB 37585, Linwe, Locality AM78, latex cast of ventral exterior, x 4. Figs 9-11 Dirafinesquina globosa gen. et sp. noy. Linwe, Locality AM78. 9a—c, BB 37607, lateral, posterior and ventral views of ventral internal mould, x 1.5. 10, BB 37600, latex cast of dorsal interior showing the cardinalia and muscle field, x 5. 11a, 11b, BB 37593, Holotype, latex cast and internal mould of dorsal interior, x 5. 126 three ventral valves are measured here. L WW ILIA Ma TE IAL, WIL AYIA BB37606, ventral valve 23.9 23.7 1.01 13.2 055 92 0.39 BB37607, ventral valve 23.7 23.6 1.00 10.8 046 8.8 0.37 BB37619, ventral valve 20.6 205 1.00 89 043 7.8 0.38 DISCUSSION. A dorsal valve (Reed 1936: 69, pl. 3, fig. 6) was identified as Rafinesquina cf. alternata Conrad and a ventral valve (Reed 1936: 70, pl. 3, fig. 7) identified as R. cf. semiglobosina Davidson; both were from the Bawzaing Horizon (equivalent to the Naungkangyi Group) of Sinchaung, Southern Shan States: both are similar to our present material. R. alternata, the type species of Rafinesquina from the Hudson River Group (Caradoc) at Cincinnati, Ohio, U.S. A., differs from the Burmese material in having a larger shell, much less differentiated but denser costellae, and less im- pressed ventral muscle field, as well as the generic differences mentioned above. The true semiglobosina (see Reed 1917: 869, pl. 12, figs 13-20) has cardinalia of Type A and well-developed dorsal transmuscle ridges and has been reassigned to the furcitellid Dactylogonia by Williams (1962: 201) and Cocks (1978: 120). So we propose a new species globosa for our specimens, in which we provisionally include Reed’s two exteriors. The specimens illustrated as Rafinesquina imbrex Pander by Reed (1906: 52, pl. 5, figs 9-12), from the Naungkangyi Group at Tawmawgon in the Northern Shan States, have cardinalia of Type A, well-developed dorsal muscle-bounding ridges and a strong median septum, and so they are within the subfamily Furcitellinae. The dorsal exterior identified as Rafinesquina cf. richardsoni Reed by Reed (1936: 37, pl. 3, fig. 9), from the rocks corresponding to the Naungkangyi Group at Hpongyi Kyaung in the Southern Shan States, differs from our new species in having a much more trans- verse shell and denser costellae. Compared with the true richardsoni (Reed 1917: 868, pl. 12, figs 11, lla, 12) from the Whitehouse Group (Caradoc) at Shalloch Mill, Girvan, its ornament is more differentiated and denser, although they are similar in shell outline. Since no internal moulds are available, the specimen has not been reidentified here. Subfamily LEPTAENINAE Hall & Clarke, 1894 Indet. leptaenines PI. 5, fig. 4 DISCUSSION. One exterior (BB37744), from the Li-lu Formation (equivalent to the Upper Naungkangyi Group) at Ta-Pangtawng (about 10 km east of Longtawkno), Northern Shan States, has well- differentiated parvicostellae with 6—8 finer costellae between two coarser ones, evenly populated growth lines 18 per mm, and concen- tric rugae, and appears to be a leptaenine. Two specimens from the Naungkangy1 Group at Ledet and Lebyaungbyan (about 7 km west of Maymyo), Northern Shan States, identified by Reed (1906: 55, pl. 4, figs 39-41) as the new species Leptaena? ledetensis, have stronger PLATE 5 L.R.M. COCKS AND ZHAN REN-BIN and fewer coarse costellae which cut through all the concentric rugae, and a distinctive ventral interior, so Jedetensis should prob- ably be reassigned to some other genus, possibly outside the Rafinesquinidae. Reed (1936) also identified three species of Leptaena, all on the basis of single specimens from rocks corre- sponding to the Naungkangyi Group in the Southern Shan States. The specimen Reed (1936: 33, pl. 3, fig. 3) called L. cf. juvenilis Opik has undifferentiated costellae and strong concentric rugae which bend suddenly posteriorly at a sharp re-entrant angle in the valve centre, but the true juvenilis from Estonia (Opik 1930: 173, pl. 11, figs 140-141; pl. 12, figs 142-145) has parvicostellae and concentric rugae not bending in the middle: however, Reed’s Bur- mese specimen might be assigned to Leptaena (Leptaena). The Leptaena cf. richmondensis Foerste of Reed (1936: 34, pl. 3, fig. 11) isa ventral valve which 1s different from Foerste’s true richmondensis (1909: 211, pl. 4, figs 10OA, B) from the Waynesville Formation of Madison, Indiana, U.S.A., in having a different shell outline, well- differentiated parvicostellae and less developed concentric rugae. We also assign it to Leptaena (Leptaena), but it is not certain whether or not the various Burmese specimens belong to the same species. Leptaena spectata Reed (1936: 34, pl. 3, fig. 12), from the Naungkangyi Group of Taungtala, Southern Shan States, is founded on a single distorted ventral internal mould although it is similar to our specimen in ornamentation; but we cannot properly characterise Reed’s species without more material, and thus leave the one or more leptaenine species from the Naungkangyi Group in open nomenclature. Family GLYPTOMENIDAE Williams, in Williams ef al., 1965 Subfamily GLYPTOMENINAE Williams, in Williams et al., 1965 Genus GLYPTOMENA Cooper, 1956 Glyptomena sp. Pl. 5, fig. 6 DISCUSSION. A single concave dorsal valve (external and internal mould, BB37586), from the equivalents of the Upper Naungkangyi Group at Linwe (Locality AM78), Southern Shan States, has a pair of small, discrete and sessile cardinal process lobes with straight socket ridges fused directly onto their lateral bases, which is typical of Glyptomena. Little can be seen on the external and internal moulds except for the cardinalia. Superfamily PORAMBONITOIDEA Davidson, 1853 Family SYNTROPHOPSIDAE Ulrich & Cooper, 1936 Indet. syntrophopsid PISo; tiga DISCUSSION. One slightly distorted ventral valve (BB37691), from the equivalents of the Upper Naungkangyi Group at Loke-pyin (about 14 km southeast of Ye-ngan, Locality AM106), Southern Figs 1-3, 5 Dirafinesquina globosa gen. et sp. nov. Linwe, Locality AM78. la—d, BB 37619, latex cast, and anterior, ventral and posterior views of ventral internal mould, x 2. 2a, 2b, BB 37606, posterior and ventral views of ventral internal mould, x 1.5. 3, BB 37612, ventral internal mould, x 5. 5, BB 37604, ventral internal mould, showing the muscle field, x 2. Fig. 4 Indeterminate leptaeninid. BB 37744, Ta-Pangtawng, Locality YA454.1, latex cast of dorsal exterior, x 2. Fig. 6 Glyptomena sp. BB 37586, Linwe, Locality AM78, 6a—c, latex cast and internal mould of dorsal interior, and dorsal external mould, x 3, x 2, x 2. Fig. 7 Indeterminate syntrophopsid. BB 37691, Loke-pyin, Locality AM106, latex cast and internal mould of ventral interior, x 5, x 10. Figs 8—9 Porambonites spp. 8, B 29671, Lebyaungbyan, ventral internal mould, x 1.5. 9a, 9b, SMA 3133, Sedaw, ventral and dorsal views of conjoined valves, x 1.5. CARADOC BRACHIOPODS FROM THE SHAN STATES 127 128 Shan States, has a smooth shell, a mostly sessile spondylium and a short median septum originating near the anterior end of the spondylium, all of which are typical of Syntrophopsis Ulrich & Cooper (1936: 630). Among the 12 species recognized by Ulrich & Cooper (1938) within Syntrophopsis, S. laevicula (p. 233, pl. 50, figs 22-28), from the West Spring Creek Formation (late Arenig) of Oklahoma, U. S. A., is most similar to our specimen, but without more material, particularly the dorsal interior, no further identifica- tion is possible. Family PORAMBONITIDAE Davidson, 1853 Genus PORAMBONITES Pander, 1830 Pl. 5, figs 8-9 MATERIAL AND LOCALITIES. One individual, SMA 3133, with conjoined valves from Sedaw (about 15 km northwest of Kyaukme) and one ventral internal mould, B 29671, from Lebyaungbyan (about 7 km west of Maymyo), both from the Naungkangyi Group of the Northern Shan States. Porambonites spp. DESCRIPTION. Subquadrate dorsi-biconvex shell. Straight hinge line about two-thirds of shell width, round cardinal extremities; maximum width at mid-length. Dorsal fold originating from the umbo; ventral sulcus starting at about mid-length and widening anteriorly to two-thirds shell width. Uniform costellae 4 per mm near the anterior margin. Thin, high and subparallel dental plates to about 40% of shell length; a low transverse ridge connecting their two anterior ends forming a sessile pseudospondylium. DISCUSSION. Williams ef al. (1965: H532) accepted P. interme- dius Pander (1830) as the nominate type species but pointed out that P. reticulatus Pander (1830) represents the distinctive characters of this genus. The specimens from Burma have some crucial features of Porambonites, i.e., the outline, sulcus and the sessile pseudospondylium in one specimen. The individual illustrated and recognised by Reed (1906: 68, pl. 5, figs 15, 15a, 15b) as P intercedens Pander, from the same locality and horizon as ours, has a globular outline, weaker fold and sulcus, and denser radial orna- mentation. P. sinuatus Reed (1915: 14, pl. 3, figs 4-5), named on the basis of a ventral valve from the Upper Naungkangyi Group at Man- ngai of the Northern Shan States, has a much deeper sulcus and a pair of divergent dental plates. Reed (1936) also recognised two species from rocks corresponding to the Naungkangyi Group in the South- ern Shan States. P. cf. acutiplicata Reed from Konleau (Reed 1936: 48, pl. 3, figs 1-2) has a much more transverse shell with compara- tively shorter hinge line and deeper sulcus originating from the umbo and might also be referred to Porambonites sp. The true acutiplicata Reed (1917: 68, pl. 22, figs 10-11) from Girvan, Scotland, is more circular with a longer hinge line. P. cf. wahli Heinrichson from Ye-o-sin (Reed 1936: 49, pl. 3, fig. 15) has a more circular shell, a weaker fold and much denser costellae, which is very similar to Heinrichson’s true wahli (1932: 159, pl. 2, figs 1-4) from the Caradoc of Estonia, so Reed’s identification is suitable in the absence of more material. Specimens of P. triquetrus Xu, Rong & Liu (1974: 153, pl. 66, figs 34-35) from the Shihtzupu Formation (early Caradoc) at Zunyi, Guizhou, South China, are very similar to our material except for their shorter hinge line and weaker fold and sulcus. As mentioned under the indeterminate clitambonitid above, the two specimens illustrated as Clitambonites cf. squamata by Reed (1906: 66, pl. 5, fig. 14) and Clitambonites ct. ascendens by Reed (1936: 31, pl. 3, fig. 14) may also represent a species of L.R.M. COCKS AND ZHAN REN-BIN Porambonites, but it appears to be a different species from our illustrated specimens and also from P. sinuatus. In summary, there are not enough Naungkangyi specimens of Porambonites to identify the species with confidence, and it appears that there may be three or even more different species in our material. Superfamily LISSATRYPOIDEA Twenhofel, 1914 Family PROTOZYGIDAE Hall & Clarke, 1893 Subfamily PROTOZYGINAE Hall & Clarke, 1893 Genus PROTOZYGA Hall & Clarke, 1893 Protozyga? haydeni Reed, 1936 1936 Protozyga haydeni Reed: 51, pl. 4, fig. 12. DISCUSSION. Although there are no atrypoids in our new material, a distinctive dorsal valve from rocks corresponding to the Naungkangyi Group at Taunggyi in the Southern Shan States, was illustrated by Reed (1936: 51) as Protozyga haydeni. This was reassessed by Copper (1986: 834) as P.? haydeni Reed and we agree. In addition, Reed also figured a single pair of external moulds (1936: 52, pl. 5, figs 9-10) from the same locality and horizon as P? haydeni which he identified as Protozyga? cf. obsoleta Foerste, but which we consider unidentifiable. Subfamily CYCLOSPIRINAE Schuchert, 1913 Genus CYCLOSPIRA Hall & Clarke, 1893 Cyclospira sp. 21932 Hyattidina sp. Reed: 206, pl. 3, figs 17-18. 1936 Cyclospira? sp. Reed: 52, pl. 4, fig. 13. DISCUSSION. Reed (1936) figured a ventral valve as Cyclospira? sp. from rocks corresponding to the Naungkangyi Group at Taunggyi in the Southern Shan States. Although Reed’s identification queried the genus, it appears from Reed’s figures that the specimen should be included within Cyclospira. Ventral and dorsal valves from rocks corresponding to the Naungkangyi Group at Taunggyi, Southern Shan States, figured by Reed (1932) as Hyattidina sp., might also be included here. ACKNOWLEDGEMENTS. We thank A.H.G. Mitchell and B.J. Amos for the new collections, which they presented to the Natural History Museum, and to R. B. Rickards for the loan of material from the Sedgwick Museum, Cam- bridge. ZRB acknowledges a grant from the Academia Sinica to undertake the work at the Natural History Museum. Thanks to P. Crabb, NHM Photo Unit, for photography. REFERENCES Bancroft, B.B. 1928. On the notational representation of the rib-system in Orthacea. 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Bulletin of the Museum of Comparative Zoology, Harvard, 68: 255-292, pls 1-3. Williams, A. 1962. The Barr and Lower Ardmillan Series (Caradoc) of the Girvan District, south west Ayrshire, with descriptions of the Brachiopoda. Memoirs, Geological Society of London, 3: 1-267, pls 1-25. 1963. The Caradocian Brachiopod Faunas of the Bala District, Merionethshire. Bulletin of the British Museum (Natural History), Geology, London, 8 (7): 327-471, pls 1-16. & Wright, A.D. 1963. The classification of the *‘Orthis testudinaria Dalman’ group of brachiopods. Journal of Paleontology, Tulsa, 37 (1): 1-32, pls 1-2. Williams, A. ef al. 1965. Treatise on Invertebrate Paleontology, H. Brachiopoda, University of Kansas Press, 927pp. Winchell, N.H. & Schuchert, C. 1893. The Lower Silurian Brachiopoda of Minnesota. The Geology of Minnesota, Minnesota Geological and Natural History Survey, Final Report, 3: 333-374 (Entire volume dated 1895). Woodward, S.P. 1852. A manual of the Mollusca; or rudimentary Treatise of recent and fossil shells. xvi + 486pp., 24pls. London. Wright, A.D. 1964. The Fauna of the Portrane Limestone; part 2. Bulletin of the British Museum (Natural History), Geology, London, 9: 157-256, 11 pls. Xu Han-kui, Rong Jia-yu & Liu Di-yong 1974. Ordovician Brachiopods. /n: Nanjing Institute of Geology and Palaeontology, Academia Sinica (ed.), Handbook of Stratigraphy and Palaeontology in Southwest China, Beijing, 144-154, pls 64-66 (in Chinese). Zhan Ren-bin & Cocks, L.R.M. 1998. Late Ordovician brachiopods from the South China Plate, and their palaeogeographical significance. Special Papers in Palaeon- tology, 59: 1-70, pls 1-9. 130 APPENDIX Rong etal. (1995) compared various affinity indices and found most useful those by Otsuka [AI=C/(N,N,)!”], Dice [AI=2C/N,4N,)] and Fager [AI=C/(N.N,)'—-1/(2(N,)')]. In each formula N, is the total number of genera of one fauna, N, is the number of genera of another fauna and C is the number of genera common to both faunas, supposing N, is larger than N,. We have calculated the affinity indices between the eight faunas by all three methods and Table | shows each index in the lower diagonal and their average in the upper diagonal. Below are the lists of faunas used in the calculation of affinity indices: 1. Shihtzupu Formation (early Caradoc), northwestern Guizhou, South China (Xu eft al. 1974, with some additional material collected by R. P. Tripp in the Natural History Museum, London): Philhedrella sp.; Lingulella sp.; Nicolella actoniae; N. delicata; Saucrorthis minor; Skenidioides sp.; Peritritoechia imbricatia; Gonambonites nobilis; Leptellina sinensis; Aegironetes minuta; Anoptambonites sp.; Chonetoidea sp.; Leptaena qianbeiensis; Platymena? mutabilis; Bellimurina rudis; Rafinesquina? sp.; Kiaeromena sp.; Glyptomena sp.; Syntrophopsis sp.; Porambonites triquetrus; P. transversus. . Pingliang Formation (late Caradoc), Longxian, Shaanxi Prov- ince, Northwest China (Fu 1982, Rong & Zhan 1996): Paracran- iops sp.; Dolerorthis sp.; Bicuspina regularis; Glyptorthis sp.; Skenidioides sp.; Anisopleurella sp.; Leptestiina longxianensis; Leangella (Leangella) sp.; Sowerbyella cf. sladensis; Leptaena sp.; Gunnarella gigantea; Bellimurina quadrata; Kiaeromena longxianensis; Foliomena inelegans; Christiania longxianensis; Nubialba sp.; indet. pentameroid; Longxianirhynchia transversa; Cyclospira sp. 3. Sargaldak Formation and its contemporary Anderken Formation (middle to late Caradoc), Chingiz, Kazakhstan (Klenina ef al. 1984): Ectenoglossa sorbulakensis; Tuvinia extrema; Archae- orthis opima; Productorthis sp.; Austinella grandis; Perimeco- coelia semicostata; Aulie convexa; Sowerbyella rukavischnik- ovae; Ptychoglyptus sp.;Dulankarella aff. magna; D. namasensis; D. subquadrata; Craspedelia sp.; Leptaena (Leptaena) tarbagataiensis; Eoanastrophia extenuata; Camerella plicata; Rhynchotrema perspica. 4. Khankhar Horizon (Caradoc), Gorny Altai, Russia (Kulkov & Severgina 1989): Orthambonites jaboganicum; Altaeorthis uscutchevi; Hesperorthis concava; Boreadorthis togaensis; Glyptorthis altaica; G. balclatchiensis; Eridorthis subinexpecta; Multicostella (Chaulistomella) inaequistriata; M. (C.) amzassensis; Plectorthis apertus; P. altaicus; Plectorthis sp.; Mimella sp.; Severginella altaica; Paurorthis sibirica; Onniella in) L.R.M. COCKS AND ZHAN REN-BIN chancharica; Triplesia mongolica; Palaeostrophomena sp.; Sowerbyites cf. lamellosus; Titanambonites elandicus; Iso- phragma ricevillense; Leangella scissa; Sowerbyella (Sowerby- ella) sibirica; Bimuria bugrychiensis; Dactylogonia subgeni- culata; Eoanostrophia lebediensis; E. aft. kurdaica; Togaella grandis; Rhynchotretoides aincus; Rostricellula lapworthi; R. ainsliei amzassica; R. exilis. . Nant Hir Group and Derfel Limestone (Caradoc), Bala District, Wales (Williams 1963): Lingulella cf. ovata; Pseudocrania cf. divaricata; Paracraniops macella; Orbiculoidea sp.; Orthambonites cessata; Nicolella actoniae; N. actoniae obesa; Dolerorthis duftonensis prolixa; Dolerorthis sp.; Dinorthis flabellulum; D. berwynensis; D. berwyensis angusta; Platys- trophia cf. sublimis; Rhactorthis crassa; Skenidioides cf. costatus; Cremnorthis parva; Dalmanella modica; Howellites striata; H. intermedia; H. ultima; H. antiquior; Onniella ostentata; O. cf. soudleyensis; Bancroftina sp.; Reuschella cf. horderleyensis; R. horderleyensis undulata; Heterorthis alternata; H. cf. retrorsistria; Salopia sp.; Bicuspina spiriferoides; Oxoplecia sp.; Vellamo sp.; Leptestiina oepiki; Sowerbyella sericea; S. soudleyensis; S. musculosa; S. sericea permixta; Eoplectodonta cf. rhombica; Sericoidea sp.;Strophomena grandis; Strophomena sp.; Glyptomena cf. osloensis; Macrocoelia expansa; M. prolata; Hedstroemina? spp.; Leptaena salopiensis; L. ventricosa; Kiaeromena cf. kjerulfi; Bellimurina incommoda; Rostricellula sparsa; Cyclospira sp. . Cliefden Caves Limestone Group and equivalents (Caradoc), central New South Wales, Australia (Percival 1991): Hesperorthis barbata; Ptychopleurella decretoria; Eridorthis australis; Dinorthis hadra; Bowanorthis fragilis; Plectorthis cliefdenensis; Doleroides mixticius; Phaceloorthis decoris; Boonderella fasciculata; Skenidioides quondonensis; Paraonychoplecia inversa; Sowerbyites isotes; Wiradjuriella halis ; Anoptambonites exedra; Tylambonites speciosa; Sowerbyella billabongensis; Oepikina? walliensis; Trigrammaria ampla; Quondongia alitis; Molongcola variabilis; Christiania skolia; Didymelasma inconspicua; Rhynchotrema oepiki; Protozyga definitiva; Webbyspira principalis; Zygospira carinata; Australispira disticha. 7. Advance Formation (Caradoc), northern Rocky Mountains, Brit- ish Columbia, Canada (Jin & Norford 1996): Plaesiomys aff. subquadratus; P. meedsi; Dinorthis cf. holdeni; Glyptorthis assimilis; Scaphorthis perplexa; Platystrophia colbiensis; Paurorthis ponderosa; Paucicrura rogata; Oxoplecia globularis; Glyptambonites musculosus; Leangella (Leangella) biseptata; Christiania subquadrata; Bimuria cf. superba; Thaerodonta redstonensis; Eoplectodonta (Eoplectodonta) alternata; Stropho- mena cf. planumbona; Rafinesquina praecursor; Murinella cf. biconvexa; Oepikina sp.; Parastrophina sp.; Hiscobeccus mackenziensis; Anazyga bellicostata. Bull. nat. Hist. Mus. Lond. (Geol.) 54(2): 131-146 Issued 26 November 1998 A review of the stratigraphy and trilobite faunas from the Cambrian Burj Formation in Jordan A.W.A. RUSHTON YZ Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD J.-H. POWELL British Geological Survey, Keyworth, Nottingham, NG12 5GG Synopsis. The Burj Formation in Jordan, and its correlatives in surrounding countries, is a Cambrian marine carbonate and siliciclastic deposit which transgressed widely but relatively briefly southwards across the Arabian craton. Three members (Tayan Siltstone, Numayri Dolomite and Hanneh Siltstone) are here formally described from outcrops at the southern end of the Dead Sea, Jordan. Trilobites from the Burj Formation are described and are all considered to be earliest Middle Cambrian in age, rather than Lower Cambrian, as previously recorded. INTRODUCTION The lithostratigraphy of the Cambrian System in Jordan has been studied extensively (Bender 1974; Powell 1989). In outline, Neoproterozoic complexes (Ibrahim & McCourt 1995) are overlain by the Ram Group, which consists dominantly of sandstone units and includes a fossiliferous carbonate-rich intercalation now known as the Burj Formation. Faunas from the Burj were examined by various workers who tentatively assigned early to mid- or late Cambrian and Ordovician ages to them. Contemporaneous beds which crop out at Timna in the southern Negev (south Israel) have been reviewed by Weissbrod (1970) and Parnes (1971); the Timna outcrop is generally accepted as being offset from the Dead Sea outcrop in Jordan by a left-lateral (sinistral) displacement of approxi- mately 105 km along the Dead Sea — Gulf of Aqaba Rift fault (Freund et al., 1970). Brachiopods and trilobites recorded from the Burj Formation by Blanckenhorn (1912, 1914) were described by Richter & Richter (1941), who reviewed other work in that region. They rejected earlier opinions that the faunas ranged in age from early in the Cambrian to Ordovician, and regarded the records known to them as close to the Lower-Middle Cambrian boundary, and probably high- est Lower Cambrian. Parnes (1971) described further material, especially from the southern Negev, and reviewed earlier work. After comparing material from the east side of the Dead Sea and from Timna in the southern Negev with Hupé’s faunal succession for Morocco (Hupé 1960), he proposed a more elaborate biostratigraphy extending through much of the Lower Cambrian. Cooper (1976) studied the brachiopod faunas and relied on Parnes’ work to indicate their late Early Cambrian age. Subsequent seismic studies and the examination of deep boreholes has greatly extended knowledge of the Cambrian succession in Jordan (Andrews 1991). Although the macrofossils were considered to indicate a late Early Cambrian age for the formation, marine palynomorphs described from boreholes NH-1, TS-11, WS-3 in Jordan (Fig. 2), occurring in palynozone JC-1 of Keegan et al. (1990), were assigned an early Middle Cambrian age, especially on account of the occurrence of acritarchs known from the Oville Formation in Spain, which is assigned to the Leonian Stage (Table 1) and the overlying Caesaraugustian Stage (Linan ef al. 1993). © The Natural History Museum, 1998 KKG\2076. |) Whilst these reports suggested that the biostratigraphy of the Cambrian rocks of Jordan and Israel is complex, sedimentological syntheses, coupled with work on trace fossils, supported a relatively simple model in which a Cambrian marine transgression introduced a tongue of marine strata onto the Arabian craton (Selley 1972; Amireh ef al. 1994), though those authors did not attempt to integrate their syntheses with the known biostratigraphy. We have examined new material from the Dead Sea area and reviewed older work, especially in the light of recent study of the Moroccan sequences (Geyer 1990a, 1990b; Sdzuy 1995), and be- lieve that the palaeontological evidence can be reconciled with the recent stratigraphical and sedimentological syntheses. We conclude (following Amireh et al. 1994) that near the beginning of Middle Cambrian times a marine incursion transgressed from the north or north-west onto earlier Cambrian fluviatile deposits on the Arabian craton. It introduced various lithofacies comprising locally fossiliferous shallow-water carbonate and siliciclastic deposits. Soon afterwards a fall in sea-level and increased sediment from the Arabian craton resulted in a return to fluviatile sedimentation which continued in central-south Jordan until the Ordovician. LITHOSTRATIGRAPHY LOCALITIES. Owing to a lack of a standard transliteration of Arabic place names, confusion has arisen regarding the names of wadis and other features referred to by various authors (for example Wadi Qunai has been recorded as Wadi Quni, Wadi Kneye, Wadi Gineya). We adopt the standard names used by the Geology Direc- torate, Natural Resources Authority, Jordan. Localities studied during this work are located to within 500 m using the Palestine National Grid (PNG). Localities referred to by previous authors are not always precise, and here we have endeav- oured to give a grid reference based on their descriptions. Burj Formation The Burj Dolomite-Shale Formation, hereafter referred to as the Burj Formation, forms a prominent cliff-like feature between the siliciclastic Salib Arkose and Umm Ishrin formations in the type 132 Table 1 PERIOD/ SPAIN MOROCCO EPOCH LEONIAN O. frequens (with Zone Paradoxides JORDAN A.W.A. RUSHTON AND J.H. POWELL Correlation of the Lower-Middle Cambrian interval in Jordan with selected successions elsewhere, based on trilobite faunas. SIBERIA SOUTH CHINA Redlichia nobilis Zone Triplagnostus gibbus Zone Zz < lo) < i = mureroensis — i ic) e z a Zz : < ro cine = Cephalopyge Kounamkites Redlichia s tt < y = é ~ 5) = Zone z, | Zone (with O chinensis Zone =) = | (with < | Schistocephalus | > < i=) fe | 4 a 5 Schistocephalus © | juvenis) fo) 2“ = < cf. juvenis) le = — =) = Ae Sr a ieee RT Sl < s BILBILIAN = = DAROCA iS) =o Hupeolenus ; P. antiquus 2 | Megapalaeolenus INTERVAL Fone P. antiquus < (with K. campbelli Zone > | Zone 5) ~ Realaspis & Realaspis ic) aw Kingaspis) O. palmeri z z =a ees < jo) Zz < a oe ag Zz <_ | Anabaraspis © | Palaeolenus a | MARIANIAN | < = Sed Balizene = z. | Sectigena Zone ° vo fo} < Pa : pS) fae] [o} Drepanuroides | = Zone *Middle Cambrian of Sdzuy (1961); #Middle Cambrian of Geyer (1990) area adjacent to the Dead Sea. The general stratigraphical setting is shown in Fig. 1. The best exposures are southwards from Wadi Issal (Edh Dhira) to the Feinan-Dana area (Figs 2-4). It also crops out a few kilometres north of Wadi Zarga Ma’in where only the upper part of the formation is exposed. Between the Feinan-Dana area and Wadi Quseib the formation is represented by coeval marine siliciclastic deposits (Bender 1974; Powell 1989) but it is absent south of the latter locality and in the Southern Desert where the Umm Ishrin Sandstone directly overlies the Salib Arkose (Fig. 4). The formation has been penetrated in deep boreholes (Fig. 2) north- west of Amman (e.g. Suweileh 1, SW-1) and in the southern Wadi Sirhan (e.g. Wadi Sirhan 3, WS-3) where marine carbonate and siliciclastic deposits, equivalent to the Burj Formation, are reported to be at least 135 m thick (Andrews 1991). The Burj Formation, as defined by Powell (1989) and adopted in this paper, is probably thicker than recorded in these boreholes (Fig. 2, Fig. 4, section 1) because in them the top of the formation was generally taken at the top of the middle Numayri Dolomite Member, the Hanneh Siltstone Member not being recognised. This lower boundary produces a marked geophysical log response and is a convenient marker hori- zon for subsurface studies (Andrews, 1991). However, in the reference borehole Wadi Sirhan-3 (WS-3, Fig. 2) Andrews (1991: fig. 10) attributed a succession of marine claystone, siltstone and sandstone intercalated with dolomitic limestone and shelly, trilobite-rich, oolitic grainstones, that overlie the Numayri Dolomite, to the upper part of the Burj Formation. We concur with this interpretation and, further- more, consider these upper beds to be a lithofacies equivalent of the carbonate/siliciclastic beds in the upper part of the Burj Formation (possibly equivalent to the Hanneh Member), as described herein from the outcrop at Zarga Ma’in (Figs 2, 4). The type section in the Safi area is Khirbet El Burj, Locality 1 of Blanckenhorn (1912) (‘Chirbet el-Burdsch’ in Richter & Richter 1941). The full sequence is not well exposed at this locality so reference sections were proposed in the same area at Wadi Saramuj (PNG 198:047) (Powell, 1988) and east of Safi Potash Works (PNG 201:055) (Fig. 3). Fig. 5 shows a composite section in the type area and the Wadi Zarqa Ma’in section provides a useful reference section for the upper part of the formation in the north-central area (Fig. 6). THICKNESS. The formation ranges in thickness, at outcrop, from zero in the southern desert to 120 m in the Safi area (Fig. 4). Thicknesses recorded in deep boreholes near Amman (Fig. 2) are based on the top of the formation being taken as the top of the Numayri Dolomite Member (sensu Andrews, 1991; see above), and are consequently minimum thicknesses, as follows: 124 m in Suweileh | Borehole (SW-1 in Fig. 2) and 135 min Safra | Borehole (SA-1) (Bender 1974). Correlation of the outcrop and boreholes in the Wadi Zarqa Ma’in area (GTZ-2D Borehole; Masarwah 1987) suggests that the ‘marine’ Burj Formation is about 170 m thick, and comprises a number of carbonate units intercalated with marine siliciclastic beds; similar lithofacies, up to 96 m thick, were reported from a deep borehole (WS-3; Fig. 2) in the southern Wadi Sirhan area (Andrews 1991). In northern Syria the Burj carbonates have been proved up to about 200 m thick in Khanaser 1 Well, and have been widely traced throughout that country on seismic lines (Best et al. 1993). NOMENCLATURE. The formation was defined by Quennell (1951) and the name is taken from the ruins of Al Burj (‘the tower’) in the lower course of Wadi Al Hisa (also Hesa or Hasa). The dolomite- limestone (‘Wadi Nasb Limestone’) was first recorded by Hull (1886) in this area, and Blanckenhorn (1914) described a fuller sequence of 30 m of red and green micaceous shales and ‘marls’ (‘Hasa Shales’ of Wetzel & Morton, 1959) overlain by 30 m of limestone and dolomite; this definition was followed by Burdon (1959), who, with Quennell (1951), assigned group status to it. STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 133 Bonne TIMNA (isRAEL) after Lloyd, 1969; Selley, 1970 Powell, 1988; Masri, 1988) (Weissbrod, 1970 ) KUSHSHA SANDSTONE FM SILURIAN LLANDOVERY Ratiya Sst. Mbr. Batra Mst. Mbr. Tubeiliyat Sst. Mbr. ‘lower’ MUDAWWARA SANDSTONE FM DUBEIDIB SANDSTONE FM. LLANDEILO | CAR.-ASH. HISWAH SANDSTONE FM. LLANVIRN UMM SAHM SANDSTONE FM. ARENIG DIS! SANDSTONE FM. UMM ISHRIN SANDSTONE NETAFIM FM FM. 5 SHEHORET FM H h XK = anne D Gl ee Nanay ve ehushtan Mbr. BURJ FM Dolomite 5 FM. Nimra Mbr. T: = 4 > SALIB ARKOSE FM. AMUDEI SHELOMO FM FEINAN GRANITE & AHEIMIR il ? WOFeANIGS ZENEFIM/EILAT FM %2|ga] _HIVALA VOLCANICLASTICS f°] SARAMUJ CONGLOMERATE AQABA © © Wt iP Ie E xX PRE- CAMBRIAN BASEMENT Fig. 1 Stratigraphical framework of the Cambrian and Ordovician rocks in Jordan and Israel (after Powell, 1989). Bender (1974) termed it the “dolomite-limestone-shale formation’ and followed the definition of Blanckenhorn (op. cit.). However, in lithological sections and maps Bender (1968) included about 30 metres of overlying shales and sandstone (cb 2+1) within the same formation. The latter definition was adopted by Powell (1988) and is followed here, although in the subsurface Andrews (1991) placed the top of the formation at the top of the Numayri Dolomite. Powell recognised three members, in upwards sequence: the Tayan Siltstone, Numayri Dolomite and Hanneh Siltstone, described below, from the type area near Safi (Figs 3-5). The Burj Formation is equivalent to the Timna Formation (Fig. 1) on the west side of the Wadi Araba, at Timna, near Eilat (Weissbrod, 1970). The four formations of Parnes’ (1971) review — the Hakhlil, Nimra, Nehushtan and Mikhrot formations — are here treated as members of the Timna Formation. Tayan Siltstone Member. This ranges in thickness from 18—20m, and consists of finely laminated green, mauve and red or buff, micaceous, fine-grained sandstone and siltstone. The name is taken from Wadi Tayan (PNG 201.5:061.5) where the member is well exposed (Figs 3, 5). Straight-crested, oscillation (wave) ripples, ripple cross-lamination, and parallel lamination are common. The thicker sandstone beds have small-scale, bimodal, trough cross-bedding with mudstone intraclasts. Thin dolomite lenses are present near the middle of the member, and indeterminate surface burrows are common on some bedding planes. Secondary gypsum veins and laminae occur along joints and bedding planes. The lower boundary is defined at the base of mauve-red micaceous siltstone and fine-grained sandstone that overlies yellow-brown medium-grained trough cross-bedded sandstone of the Salib Arkose Formation. The upper junction with the Numayri Dolomite is taken at the base of the first thick bed of limestone or dolomitic limestone, which in places is sandy, with low-angle erosive scours and ripple cross-lamination. Numayri Dolomite Member. The member (38 to 60 m thick) forms a prominent, brown-weathering cliff along the outcrop. The name derives from Wadi Numayri (PNG 203:059) where it is well exposed. The carbonate varies from limestone to dolomitic lime- stone and dolomite with wackestone and packstone textures; clasts include ooliths and bioclasts (brachiopods, hyolithids and trilo- bites). The vertical sequence of microfacies varies throughout the outcrop, but the following generalised sequence is common to most exposures in the Safi — Wadi Numayri areas: the basal 5 m has a high proportion of fine-grained quartz sand with ripple cross-lamination and sandstone intraclasts; this passes up to a massive, brown- weathering (grey) dolomite and dolomitic limestones (microcrystalline, wackestone and packstone textures), 20-30 m thick, with glauconite peloids, cross-laminated and parallel-lami- nated oolites, oncolites (algal-coated grains), and lenses of disarticulated brachiopods and rare trilobite fragments. Irregular lenses of orange-brown dolomite are intercalated with the clast-rich carbonates. There is an increase in quartz sand above, with alternat- ing sand-rich and sand-poor lenses; the sand-rich lenses are cross-laminated, with shallow erosive scours and they weather as prominent dark brown chert-like bands, 2—3 m thick. Beds of oolitic, oncolitic or brachiopod shell-rich dolomicrite limestone are locally present at the top of the member in the south. Near Safi (Figs 4, 5), the member is thicker (58 m) and the upper part includes beds of cross-laminated oolitic limestone, algal stromatolites, and thin (40 cm) beds of green calcareous siltstone with abundant trilobite fragments, hyolithids and glauconite peloids. Here, the sequence is capped by a distinctive orange-weathering dolomite. The textures and fine details of the carbonates are often obscured at outcrop by ubiquitous brown staining. The boundary with the green, red or grey micaceous siltstone or fine-grained sandstone of the overlying Hanneh Siltstone is sharp. Hanneh Siltstone Member. The name is taken from Jibal Tabaq Hanneh (PNG 201.5:060.0), on the north side of Wadi Numayri (Fig. 3). The lithology of this member is similar to the Tayan Siltstone, but there is a higher proportion of sand over silt-grade siliciclastic rocks. It was not previously included in the formation, except for the maps and lithological sections in Bender (1968). It is about 30 m thick in the Wadi Saramuj area and 35 m thick in the cliffs below Jibal Tayan. The base is sharp, and is taken where red-grey or green parallel-laminated to ripple cross-laminated micaceous siltstone overlies the carbonate (Numayri Dolomite). The beds above are laterally variable, but predominantly comprise thinly bedded green or red-green, micaceous, ripple cross-laminated siltstone and micaceous fine-grained sandstone, with thicker beds (0.5 m) of buff, medium-grained, bimodal trough cross-bedded sandstone; mudstone and dolomite clasts are common at some horizons. Small, circular surface-burrows and Rusophycus(?) traces are present on siltstone surfaces. The top is clearly marked by the overlying red-brown, massive, medium- to coarse-grained, large- scale trough cross-bedded sandstone (Umm Ishrin Formation). A.W.A. RUSHTON AND J.H. POWELL 36 37 . 7 a = : 22>. 2c ay. 4 BS | < s aos we uy E 27 | (ie | S >> noston 49 D Pa) pa ey UMM ISHRIN Sa) oR A a Se ae , aot = 5 = Lease Sy? eo KHUSHEIBA eS fe) J] SANDSTONE BURJ a 5 Be FORMATION ARABA COMPLEX ) @ Middle Cambrian Precambrian Ee Bas to Lower Cambrian? Oo 39 siltstone i.ts|] sandstone fez2| pebbly sandstone “ah => LY S, HY limestone SF OY Bae es 50 VERTICAL - nu fed dolomitic limestone c SARAMUJ and dolomite SCALE m / CONGLOMERATE [45] trough cross-bedding “0 —TN Precambrian to Lower Cambrian’ ripple cross-lamination Location of sections 95 4 | Fig. 4 Correlation of the Ram Group, including the Burj Formation, along the margin of the Dead Sea — Gulf of Aqaba Rift. Inset map shows the location of the sections. HS = Hanneh Siltstone, KS = Kusheiba Sandstone, ND = Numayri Dolomite, TS = Tayan Siltstone (after Powell, 1989). LITHOLOGY FOSSILS KEY sandstone siltstone Ai limestone dolomitic limestone 5-4) dolomite ZA trough cross-bedding —n Tripple cross-lamination =< wavy bedding UMM ISHRIN | FORMATION yV¢ SSS a 2 °° ooids c at a @ oncolites = trilobites o 3 Ea i = : brachiopods = ER = hyolithids a == algal lamination non a = circular burrows ———j) QP. Cruziana oe C4 20m Fig.5 Composite lithological section of the Burj Formation in the Safi area, southern Dead Sea. Arrow shows the level with trilobites in Wadi Qunai (after Powell, 1989). intertidal environment; it was succeeded by a further pulse of tidally influenced shallow-marine siliciclastic deposition under similar conditions to those of the Tayan Siltstone further south. The pattern of southwest- to west-trending facies belts derived from deep boreholes (Andrews 1991), passing from fluvial and intertidal siliciclastic facies in south Jordan to shallow marine carbonate and intertidal siliciclastic environments in central and north Jordan, is consistent with a progressive onlap during Tayan to Numayri time. The carbonate platform can be traced in the sub- surface of north Syria (Best et al. 1993), a distance of about 700 km from the location of the palaeoshoreline in south Jordan (Fig. 2). The maximum transgression (maximum flooding) resulted in deposition of the main Numayri carbonate in the type area, passing southwards into intertidal and fluvial siliciclastic strata (Wadi Kusheiba Sand- stone). A subsequent regressive low-stand of sea-level (see Regional Correlation, below) resulted in an increased influx of sandy sedi- ment during deposition of the Hanneh unit in the type area. However, boreholes in north Jordan indicate that stratigraphically younger phases of carbonate deposition may have continued in those areas located farther offshore. A.W.A. RUSHTON AND J.H. POWELL MEMBER LITHOLOGY FOSSILS FORMATION BURJ Middle Cambrian NUMAYRI DOLOMITE/HANNEH SILTSTONE So LIE == ——} Asn PRT = “nn ral = m 0 Fig. 6 Stratigraphical section of the upper part of the Burj Formation at Wadi Zarga Ma’in, northern Dead Sea. Key as for Fig. 5, but note the difference in the vertical scales. Arrow shows the level with the trilobites figured herein. FAUNAS Fossils are reported from the following sites: 1. WADI ZARQA MAT‘IN. A section 800 m north of Wadi Zarga Ma’in (PNG 204.4:501.3) contains thin calcarenite beds. These have yielded: ‘Hyolithes’ kingi Richter & Richter, 1941 [type locality] Kingaspis campbelli (King, 1923) [type locality; described herein] Palaeolenus antiquus (Chernysheva, 1956) [described herein] ‘Hyolithes’ kingiis apparently identical toHyolithes fouchouensis moabiticus described from the same locality by Picard (1942), presumably in ignorance of the Richter & Richter (1941) paper. WADI RIMEILEH, King’s (1923) locality (43 (PNG 201:061), 1.6 km south of Wadi ‘Esal’ (=Issal); this is approximately the same locality as Wadi At Tayan (Fig. 3), described herein. From micaceous siltstone: Onaraspis palmeri (Parnes, 1971) It appears that the original material of Realaspis? orientalis in) STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 137 (Picard, 1942) came from the same locality, though not neces- sarily the same stratum. 3. WADI QUNAI. Section 2 km east of Arab Potash Works, Safi (PNG 201.5:055.6) (Fig. 3): Lingulate? brachiopod with divaricate sculpture ‘Hyolithes’ cf. kingi (Richter & Richter, 1941) Realaspis sp. nov. [described herein] Redlichops blanckenhorni Richter & Richter, 1941 [described herein] 4. WADI SARAMUJ (PNG 198:047) (Fig. 3): Psiloria alata (King, 1923) [type locality] Trematosia radifer (Richter & Richter, 1941) [type locality] ‘Hyolithes’ sp. The brachiopods were described by Cooper (1976). 5. KHIRBET EL-BURJ (PNG 198:047) (Fig. 3): Trematobolus palastinensis Richter & Richter, 1941 [type locality } Trematosia radifer (Richter & Richter, 1941) ‘Hyolithes’ sp. Hesa problematica Richter & Richter, 1941 [type locality] Redlichops blanckenhorni Richter & Richter, 1941 [type locality; described herein] 6. AL ABRASH, Ghor-es-Safi; exact locality and PNG reference not known. Psiloria dayi Cooper, 1976 [type locality] Trematosia radifer (Richter & Richter, 1941) Kingaspidoides cf. obliquoculatus Geyer, 1990b [described herein] Farther south, from the Timna area in Israel, Parnes (1971) described several trilobites, namely species of Strenuella and the new genus Timnaella, together with “Myopsolenus’ palmeri Parnes for which the type locality is Har ‘Amram, south of Timna. The material is fragmentary and poorly preserved, and correlation is uncertain, but we have confirmed Parnes’ (1971: 204) suggested identification of King’s ‘asaphid’ from Wadi Rimeileh with his Onaraspis [Myopsolenus] palmeri, which we take to be of about the same age as the beds at Wadi Qunai. Cooper (1976) described nine brachiopods from the Timna area, none of which have yet been identified from around the Dead Sea. REGIONAL CORRELATION The problem of recognising the Early-Middle Cambrian boundary is discussed by Geyer & Palmer (1995). If the presence of Paradoxides s.\. is used to recognise the Middle Cambrian, the appearance of Acadoparadoxides in Morocco at a level consider- ably lower than that indicated by earlier workers (e.g. Hupé 1960) implies that previous records of Lower Cambrian faunas may now need to be re-classified as Middle Cambrian — an opinion already expressed by Opik (1975). The interval affected approximates to the lower Amgan (Table 1) of the Siberian succession and includes the Protolenus Zone of North Atlantic (Avalonian) successions. At present no internationally agreed standard has been adopted (Geyer & Palmer 1995: 462), but in the present paper the Moroc- can usage of Geyer (1990a) and Geyer & Palmer (1995) is adopted to facilitate correlation in the Mediterranean area. In 1990 Geyer took the base of the Middle Cambrian at the base of the Hupeolenus Zone, although Geyer & Palmer (1995) showed Paradoxides s.1. extending down into its uppermost part only. In the following discussion reference is made to the stratigraphical successions shown in Table 1. WADI ZARQA MA’IN. The two trilobites recorded from Wadi Zarqga Ma’ in are known elsewhere. In Siberian sections on the rivers Amga and Lena Palaeolenus antiquus characterises the antiquus Zone, the basal zone of the Middle Cambrian as traditionally recognised there, and the range of Schistocephalus juvenis lies immediately above that of P antiquus. In Morocco S. cf. juvenis occurs with Acadoparadoxides in the Cephalopyge Zone (Sdzuy 1995), and it is assumed that the P. antiquus Zone correlates with the underlying beds, i.e. approximately the Hupeolenus Zone. Kingaspis campbelli is recorded from Morocco (Geyer 1990b: 44) in strata questionably referred to the frequens Zone (Table 1), the third zone above the base of the Middle Cambrian as recognised by Geyer (1990a).Assuming that the more reliable evidence is the Palaeolenus- Schistocephalus sequence, the upper part of the Burj Formation at Wadi Zarga Ma’in is correlated approximately with the Hupeolenus Zone. SOUTHERN END OF DEAD SEA. It is more difficult to assess the age of the Burj Formation in the type area as nearly all the fossils are known only from the Dead Sea and Rift Valley region. Kingaspidoides cf. obliquoculatus is closest to a species known from the Hupeolenus Zone in the lowest Middle Cambrian of Geyer’s (1990a) Moroccan sequence. The metadoxidid Realaspis, which has a relatively distinctive pygidium, is known by the type and only described species R. strenoides; this genus, with Pseudo- lenus, characterises the base of the Bilbilian in Spain (Linan et al. 1993), a level that has been correlated with the the lowest Middle Cambrian of Geyer, namely the Hupeolenus Zone. The fragments of Onaraspis palmeri (Parnes) from Wadi Rimeileh (= Wadi At Tayan) suggest probable correlation of the Burj Formation with the Mikhrot and/or Upper Hakhlil members of the Timna Forma- tion of the Timna area (Parnes 1971). All the other species described from that region appear to be endemic and the genera they represent are either new or stratigraphically long-ranging (Parnes 1971; Cooper 1976). DISCUSSION. The stratigraphical resolution of these faunas for wider correlation is not very good, but, so far as can be judged, they all indicate a comparatively restricted stratigraphical level close to the Lower-Middle Cambrian boundary as recognised by Geyer (1990a) and Geyer & Palmer (1995). They indicate correlation of the Burj Formation with the Hupeolenus Zone of Morocco, probably with the lower part of the Bilbilian Stage of Spain, and with the lowest part of the Amgan Stage in Siberia. Sdzuy (1995) demon- strated the correlation of overlying strata: the Cephalopyge Zone of Morocco with the lowest Leonian of Spain and the middle zone of the Amgan (Table 1). According to Linan & Gamez-Vintaned (1993: 838), strata in Spain show evidence of what they term the Daroca Marine Regres- sion during the Bilbilian Stage at a level somewhat above its base, and they attribute it to a eustatic fall of sea-level. If our correlation of the Burj Formation with the lower Bilbilian is correct, it is probable that it was the Daroca Regression which re-established fluvial deposition over Jordan and on the Arabian Craton. The sea retreated towards Turkey where, although correlatives of the Hupeolenus Zone have not been recorded, faunas of Middle Cambrian age are well described by Dean and his co-workers (e.g. Dean & Ozgiil 1994): such faunas commence with approximate correlatives of the Cephalopyge Zone, and range up through the Middle Cambrian, and confirm the persistence of marine deposition in areas to the north of Jordan and Syria. 138 SYSTEMATIC DESCRIPTIONS Superfamily REDLICHIOIDEA Poulsen, 1927 Family REDLICHIIDAE Poulsen, 1927 Subfamily PARAREDLICHIINAE Hupé, 1953 Genus REDLICHOPS Richter & Richter, 1941 TYPE SPECIES. Redlichia (Redlichops) blanckenhorni Richter & Richter, 1941, by original designation. DISCUSSION. Redlichops is a poorly known genus. When Chang [=Zhang] (1966) and Zhang ef al. (1980: 79) reviewed redlichiid trilobites they referred Redlichops with doubt to the Pararedlichiinae, mainly because both the anterior and posterior ends of the palpebral lobe are set rather far from the glabella. Even so, Redlichops differs from other Pararedlichiinae in the great width of the interocular area of the fixigena and in the recurved palpebral lobe, features matched or exceeded only by the aberrant Metaredlichiine Jingyangia (Zhang A.W.A. RUSHTON AND J.H. POWELL etal. 1980: pl. 31, figs 7, 10, 11). However, the glabella of Redlichops is not comparable with the parallel-sided or clavate glabella of the Metaredlichiinae, and the genus is here retained provisionally in the Pararedlichiinae, following Chang (in Whittington ef al., 1997: 440). Redlichops blanckenhorni Richter & Richter, 1941 Figs 7-13 1941 = Redlichia (Redlichops) blanckenhorni Richter & Richter: 15, pl. 2, figs 1, 2, 4, 5?, 6a (non figs 3, 6b) [synonymy, description]. 1997 — Redlichops (R.) (sic) blanckenhorni Richter & Richter; Whittington et al.: 441, fig. 280.1. MATERIAL. The species is based on fragmentary material from the type locality, Khirbet el Burj. Dr W. Struve kindly made available plaster casts of the holotype (Senckenberg Museum, Frankfurt-am- Main X1287a; Fig. 7) and a paratype (X1287b). New material from Wadi Qunai referred to the species is somewhat weathered but is Figs 7-13. Redlichops blanckenhorni Richter & Richter. 7, plaster cast (It.26207/1) of holotype, Senckenberg Museum X1287a, x 4. Khirbet El-Burj. 8— 13, Wadi Qunai, Safi. 8, librigena It.26211/5, x 4. 9, large cranidium, It.26209/1, x 4. 10, external mould of rostral-hypostomal plate, associated with Realaspis sp. nov. (Fig. 16), It.26212/1, x 4. 11a, b, small cranidium It.26209/3, associated with fragmentary pygidium It.26209/4 attributed to the same species; lla x 3.5, 11b x 4. 12a, b, top and side views of cranidium, It.26209/6, x 4. 13, cranidium It.26209/2, x 4. STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 139 more complete, and consists of nine cranidia and some cranidial fragments, a rostral-hypostomal plate, three librigenae, and a frag- mentary pygidium tentatively referred to this species (BM It26209, It26211-3). DESCRIPTION AND DISCUSSION. The new specimens show that, despite their fragmentary material, the Richters’ description and reconstruction of the cranidium are generally correct. The preglabellar field is slightly longer than they showed it, and in small specimens is crossed by a preglabellar ridge or plectrum; the anterior border bears faint terrace-lines parallel to the margin. The palpebral lobes in the new material are more evenly curved than in the reconstruction by Richter & Richter (1941: pl. 2, fig. 6a); in the new material they do not show the distal narrowing described by Richter & Richter, nor is this very evident in their holotype (Fig. 7). The palpebral-ocular ridge is not joined anteriorly to the glabella, nor is a parafrontal band evident; this ridge appears to slope backwards more steeply in the holotype than in the similarly sized specimen in Fig. 9, but there is some variation in this feature among the various specimens on block It.26209 (Figs 9, 11-13). The postocular section of the facial suture is very short. Where unweathered the surface is seen to be finely granulose. The rostral-hypostomal plate (Fig. 10) is abraded but resembles those of other Redlichiidae (Zhang et al. 1980: 69). If correctly assigned to this species, it shows that Redlichops is conterminant. The presence of a plectrum crossing the preglabellar field is com- monly seen in trilobites with conterminant hypostomes. The librigena (Fig. 8), confidently assigned because the course of the facial suture corresponds to that of the cranidium, is narrow, the border and the field within the border being of about the same width; in this it differs from the large fragment figured by Richter & Richter (1941: pl. 2, fig. 3), which we exclude from the species. One fragmentary pygidium (Figs 1la—b) has a long, poorly segmented axrts and the pleural field nearly as wide as the axis. There is one weak pleural groove. The surface is finely granulose and has fine striae sub-parallel to the margin. The sculpture is much less conspicuous than that of the pygidia from the same beds assigned to Realaspis. The broad interocular areas of the fixigenae and the recurved palpebral lobe make Redlichops blanckenhorni a distinctive taxon, and no closely similar species is known. At a comparable size the Pararedlichiine Eoredlichia yaoyingensis (Kobayashi) has narrower interocular fixigenae and shorter palpebral lobes, but immature forms have relatively longer, more curved palpebral lobes (Zhang et al. 1980: pl. 35, fig. 10), suggesting that the peculiarities ofRedlichops may be progenetically derived. HORIZON. Redlichops blanckenhorni is known only from Jordan and its biostratigraphical significance is not established. Pararedlichi- inae occur typically in the low Lower Cambrian but are not known to range into the Tissafin Stage which is low Middle Cambrian in Geyer’s (1990a) usage. However, Redlichops is only doubtfully referred to the Pararedlichiinae, and is here considered to lie close to the Lower-Middle Cambrian boundary, as originally suggested by Richter & Richter (1941: 27). Subfamily METADOXIDINAE Whitehouse, 1939 Genus REALASPIS Sdzuy, 1961 TYPE SPECIES. Realaspis strenoides Sdzuy, 1961, by original des- ignation. DISCUSSION. Sdzuy (1961) placed Realaspis in the Neoredlichi- inae, and Chang (in Whittington et al., 1997: 458) referred it to the subfamily Resseropinae, family Saukiandidae. However, the rela- tively broad interocular area of the fixigenae and the short palpebral lobe favour reference to the Metadoxidinae, as suggested by Opik (1968: 151). Realaspis sp. nov. Figs 15-18 MATERIAL. Four incomplete cranidia, one librigena, two pygidia, and several doubtful granulose fragments, associated with Redlichops blanckenhorni at Wadi Qunai (BM 1t26210-2). DESCRIPTION. Glabella tapered, rounded in front; glabellar fur- rows very weak, seen on the largest cranidium as faint indentations in the side of the glabella; occipital ring with small spine (Fig. 15a), occipital furrow weak. Anterior border strong, with striae sub- parallel to anterior margin. Preglabellar field practically absent, forming a depressed groove shorter than border. Palpebral-ocular ridge strong, oblique, not confluent with glabella, but in the smaller figured cranidium (Fig. 16) seems to extend into a parafrontal band. The eye extends approximately from the second glabellar furrow (S2) to the occipital furrow (SO). At level of anterior end of eye the width of cranidium is nearly three times the glabellar width at the same level; at the posterior end of the eye it is a little more than twice as wide. Interocular area of fixigena has a marked elongated interocular swelling (Pillola 1993: 859) close to the glabella. Preocular section of facial suture short, straight, subparallel or slightly divergent forwards to the anterior border furrow; posterior section very short. Surface with coarse but not very closely spaced granules. Several fragments on the same bedding planes (Fig. 17) bear the same sculpture and indicate the presence of much larger individuals than the figured specimens. Two pygidia (Fig. 18) associated with R. blanckenhorni and Realaspis sp. nov. are referred to the latter because their granulation and coarsely striate margins resemble those of the cranidia assigned to Realaspis. Outline rounded, with length two-thirds of the width. The axis occupies less than half the width and nearly the whole length of the pygidium and has one distinct and one obscure axial ring. The pleural regions have one or two pairs of weak furrows and the margin is entire; there is no semi-ankylosed anterior segment. Surface granulose, with striae near to and subparallel with the margin. DISCUSSION. The pygidia of the present taxon are fairly distinc- tive, most resembling those of the Neoredlichiinae and some Metadoxidinae, especially Realaspis strenoides Sdzuy (1961: pl. 4, figs 18-24), though it has 1—2 rather than 3 axial rings. The cranidium is also similar in outline to R. strenoides (Sdzuy 1961: 536 (254), pl. 4, figs 1-12), but shows more marked relief: in R. strenoides the anterior border and palpebral-ocular ridge are not so strong, the border furrow in front of the glabella is narrower, the eye is shorter, no interocular swellings are seen and there is no occipital spine (Whittington et al., 1997: fig. 249. 1a). The sculpture in R. strenoides is unknown, so the granulation of the present species and the striae on the anterior border cannot be compared. The present cranidia resemble some bigotinids related toHupetina Sdzuy, 1978, from the lowest trilobite zone in the Issendalen Stage of the Moroccan Cambrian (Geyer 1990a). They differ from Hupetina antiqua Sdzuy in having weaker glabellar furrows, a stronger ante- rior border and longer preglabellar field; the interocular swelling is larger and closer to the glabella than in Sdzuy’s (1978: pl. 1, fig. 7) paratype. In proportions and the weak glabellar furrows the present material is more like the unnamed cranidium from the Lemdad sectionA2, figured by Sdzuy (1978: fig. 3, top left), though that form 16 A.W.A. RUSHTON AND J.H. POWELL 15b Fig. 14 Hesa problematica Richter & Richter, holotype; plaster cast (It.26207/2) of cranidial fragment, showing parts of the preocular suture and anterior border, Khirbet El-Burj, Senckenberg Museum X1287a, x 4. Figs 15-18 Realaspis sp. noy., Wadi Qunai, Safi. 15a, b, abraded cranidium It.26210/1; 15a, whitened, shows the interocular swelling, occipital furrow and occipital node, x 3.5; 15b, unwhitened, shows the course of the facial suture, x 3. 16, small cranidium It.26212/2, x 8. 17, fragment of fixigena of large cranidium attributed to this species, showing granulation, It.26209/8, x 3. 18, two pygidia, It.26211/1 (right) and 26211/2 (left), x 4. has more divergent preocular facial sutures and no interocular swelling is shown. Few bigotinid pygidia have been described, but those of the present species are unlike those of Bigotina itself (Pillola 1993: pl. 3, figs 3, 8). The holotype of Hesa problematica Richter & Richter (1941: pl. 2, fig. 7) is a fragment of a large trilobite on the same block as the holotype of Redlichops blanckenhorni. It is unsuitable to be the formal representative of a distinct genus, but shows a slightly divergent preocular suture and a frontal border (Fig. 14) striated in much the same way as our Fig. 15; it differs because the glabella seems to indent the frontal border, a difference that seems too great to be attributed to the stage of growth. Protolenus orientalis Picard (1942: 1, pl. 2, figs 1, 2) was revised by Parnes (1971: 186, pl. 1, figs 1-4), who figured two cranidia, including Picard’s specimen. He referred the species to Resserops (Richterops) Hupé, 1953, though the form of the palpebral lobe is more compatible with Realaspis. Our material differs from R. orientalis in having a stronger, striated anterior border, a stronger border furrow, wider interocular fixigenae with stronger interocular swellings, and a coarser granulation. However, Realaspis orientalis seems to show greater resemblance to Hesa problematica, but the type material of the latter is so fragmentary that full comparison cannot be made. HORIZON. Realaspis sp. nov. occurs with Redlichops (q.v.) and there is no independent indication of its horizon. The most similar species, Realaspis strenoides, occurs at Los Cortijos, in strata of the Galician-Castilian Zone near Toledo, central Spain (Sdzuy 1961: 594), where it occurs with Pseudolenus, Kingaspis cf. velatus Sdzuy, 1961, and protolenids, which suggest the Bilbilian Stage (Linan et al, 1993: 822). Genus ONARASPIS Opik, 1968 TYPE SPECIES. ignation. Onaraspis somniurna Opik 1968, by original des- Onaraspis palmeri (Parnes, 1971) Figs 19, 20 1923 Asaphid; King: 511 [briefly described as ‘of a distinctly Asaphid type’, no figure]. 1971 Myopsolenus palmeri Parnes: 202, pls 3, 4 [described]. 1975 Myopsolenus palmeri (Parnes); Opik: 8, 9 [compared with O. somniurna; the reference on p. 8 to “Myopsolenites’ is a misprint]. DISCUSSION. The type material, from Har ‘Amram south of the Timna area, is poorly preserved and it is difficult to ascertain the characters of the species. Geyer (1990b: 175) pointed out that Parnes’ reconstruction of the cranidium differs in several respects from typical Myopsolenus, and suggested instead that it might be a member of the Bathynotidae. Considering the cranidial features, it is more like some Metadoxides (Pillola 1991: pl. 10, fig. 6), but the pygidium of O. palmeri, which has an axis of several segments and pleural fields with a broad border, is distinct from that of M. armatus (Meneghini), well figured by Pillola (1991: pl. 9, fig. 4), and more like that of Onaraspis. Opik (1975: 9) suggested that Myopsolenus palmeri was ‘the same or . . . closely related’ to O. somniurna. We STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 141 Figs 19,20 Onaraspis palmeri (Parnes), from King’s (1923) locality 83, Wadi Rimeileh. 19, pygidium, external mould, Sedgwick Museum A.59463. 20, librigena, the infill between dorsal surface and doublure shows white, Sedgwick Museum A.59464. Both unwhitened, x 1.3. accept the generic reference but the observed differences are prob- ably of specific significance: for example O. palmeri has a longer frontal area and the pleural field of the pygidium tapers backwards less strongly. King’s material from Wadi Rimeileh (Figs 19, 20) consists of a large librigena, some pleural fragments and two pygidia, of which one is complete. The specimens are fairly well preserved in siltstone and, though somewhat flattened, show granulose sculpture. The pygidium appears to agree with that of O. palmeri but is longer in proportion than that of O. somniurna, though it may be more similar to Opik’s (1968: 159) Onaraspis sp. A. HORIZON. Parnes (1971: pls 3, 4) recorded O. palmeri from the lower and upper parts of the Timna Formation, respectively from the upper part of the Hakhlil Member at Timna and from beds at Har ‘Amram that are correlated with the Mikhrot Member. The specimen from Wadi Rimeileh is from a siltstone interval in the Burj Forma- tion, but its stratigraphical relationship to other localities is unknown. Superfamily ELLIPSOCEPHALOIDEA Matthew, 1887 Family ELLIPSOCEPHALIDAE Matthew, 1887 Subamily ELLIPSOCEPHALINAE Matthew, 1887 Genus KINGASPIS Kobayashi, 1935 TYPE SPECIES. designation. Anomocare campbelli King, 1923, by original DISCUSSION. Geyer (1990b: 102) placed Kingaspis close to Ellipso- cephalus, regarding the separate family (or subfamily) Kingaspididae (or Kingaspidinae) as superfluous. He discussed the type species, K. campbelli (King) and described several other species of Kingaspis and of the closely related genus Kingaspidoides Hupé, 1953. All species of these genera have features of the cranidium effaced on the external surfaces, but axial and glabellar furrows are generally visible on internal moulds. The weakness of these furrows makes measurements taken from them rather imprecise, hampering mor- phological comparisons, but the form of the glabella, which has concave sides, expanded anterolateral corners and 4 or 5 pairs of furrows, is consistent. Kingaspis campbelli (King, 1923) Figs 21-26 1923 Anomocare campbelli King: 511, figs 3, 4 [described, illustrated with line-drawings]. 1935 Kingaspis campelli (sic) (King); Kobayashi: 196, pl. 23, figs 9, 10 [assigned to Kingaspis; poor photographs of King’s specimens, the cranidium is incorrectly restored]. 1990b Kingaspis campbelli (King); Geyer: 104, pl. 15, fig. 11, pl. 17, figs 8-10 [Moroccan specimens described and dis- cussed, with full synonymy]. MATERIAL. King’s syntype material is preserved in the Sedgwick Museum, Cambridge, and from that the cranidium SM A.1311, figured by King (his fig. 3), is here selected as lectotype (Figs 21a— c herein). Topotypic material is held in other museums (Hebrew University of Jerusalem; Senckenberg Museum, Frankfurt; Natural History Museum, London); more recently Dr J. H. Powell collected further specimens, one of which is figured here (Fig. 25). DISCUSSION. Topotypic material is well preserved and agrees with Geyer’s description. He remarked that K. campbelli has a relatively wider cranidium (1.3 times the length) than other species of the genus. There is slight variation in transverse convexity and in the evenness of the curvature in sagittal section. Geyer excluded the pygidium described by King from the species, but because it is the only kind of pygidium found with monospecific associations of the cranidia of K. campbelli, King probably origi- nally associated them correctly. King’s large paralectotype is shown here (Fig. 22). A smaller well preserved example (Fig. 26) is 5.0 mm long and estimated to have been 13 mm wide; axis more than a quarter of the total width, convex, with 3 axial rings and a trace of a fourth; pleural regions with 4 pleural furrows and three interpleural grooves; border narrows slightly backwards. Originally described from the Burj Formation at Wadi Zarqa Ma’in, topotypic specimens have since been figured many times (see Geyer 1990b: 104). HORIZON. At Wadi Zargqa Ma‘in K. campbelli is in earliest Middle Cambrian beds associated with the lowerAmgan species Palaeolenus antiquus (Chernysheva), discussed below. In Morocco it is question- ably recorded from the frequens Zone. Genus KINGASPIDOIDES Hupé, 1953 TYPE SPECIES. designation. Kingaspidoides armatus Hupé, 1953, by origianl DISCUSSION. Kingaspidoides was originally instituted for kingasp- idids with an occipital spine (Hupé 1953), but Geyer (1990b: 110) emended the diagnosis and distinguished the genus from Kingaspis by the relatively uneven convexity of the cranidium in transverse section. Kingaspidoides cf. obliquoculatus Geyer, 1990 Figs 27, 28 cf.1990b Kingaspidoides obliquoculatus Geyer: 118, pl. 18, figs 1— IIS), MATERIAL. Three cranidia from Al Abrash, Ghor-es-Safi, BM In24056-8, collected by Dr A. E. Day in 1909. Associated with Psiloria dayi Cooper (1976: 283), for which this is the type locality. DESCRIPTION AND DISCUSSION. The glabella has independent trans- verse convexity (Fig. 28e). Interocular area of fixigena scarcely convex, slopes down to palpebral lobe which is short, the posterior end lying well forward of SO. Glabella relatively narrow; at a line 142 A.W.A. RUSHTON AND J.H. POWELL Figs 21-26 Kingaspis campbelli (King), Wadi Zarga Ma’in. 21a—c, lectotype, top, front and side views of exfoliated cranidium, showing glabella and independent convexity of occipital ring, Sedgwick Museum A.1311, x 3 (figured King 1923: fig. 3). 22, paralectotype, large pygidium, Sedgwick Museum A.1310, x 3 (figured King 1923: fig. 4a). 23-26 are topotypes; 23a, b, top and front views of testate cranidium (23b, unwhitened, shows the even transverse convexity of the cranidium), In.22997/1, x 3; 24a-d, side, top, oblique and front views of partly exfoliated cranidium (24a and 24d, unwhitened, show the even convexity, 24b and 24c show the glabella and frontal border), In.22996, x 3; 25a, b, top and side views of partly exfoliated cranidium (25a shows the difference between the internal and external surface), It.26231, 25a x 4, 25b x 3; 26, latex cast of external mould of pygidium, In.22997/2, x 3. Figs 27,28 Kingaspidoides cf. obliquoculatus Geyer, ‘Al Abrash, Ghor-es-Safi’ (exact locality uncertain). 27, internal mould of fragmentary cranidium, In.24058, x 3. 28a-e, abraded testate cranidium (28a, 28b, side and top views, whitened, showing the independent convexity of the glabella; 28c-e, side, top and front views, unwhitened, showing the course of the facial suture and transverse convexity of the glabella), In.24056, 28a, 28b x 3.5, 28c—e x 3. STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 143 through the palpebral lobes it is <40% of cranidial width (Fig. 28b). No occipital spine or node. Frontal area relatively long, nearly 25% of cranidial length. Surface smooth, but the internal mould shows tiny pits (= granules on the parietal surface of the cranidium) and caeca on the preglabellar field. Among Kingaspidoides without an occipital spine, K. obliquocu- latus differs from K. neglectus Geyer (1990b: 120) in having a shorter and narrower glabella, and from K. borjensis Geyer (1990b: 122) in having a shorter palpebral lobe which does not extend back to the level of SO. HORIZON. Burj Formation, Ghor-es-Safi. K. obliquoculatus was originally described from the Asrir Formation (Hupeolenus Zone) of the Fouggara section in the Anti-Atlas Mountains, Morocco. Family PALAEOLENIDAE Hupeé, 1953 DISCUSSION. The Palaeolenidae were discussed and briefly char- acterised by Geyer (1990b: 67). The glabella is well defined and tends to be clavate and typically shows four pairs of glabellar furrows; the posterior pair (S1) curve slightly inwards and back- wards, S2 and S3 are nearly transverse, short and not connected across the glabella, and S4 is short and slightly oblique inwards and forwards. In Palaeolenus lantenoisi Mansuy, 1912, the glabella is almost parallel-sided but in P. douvillei Mansuy, 1912, the type of the genus, the glabella is slightly clavate; in both those species the preocular sections of the facial suture are approximately parallel. In P. deprati Mansuy, 1912, the type species of Megapalaeolenus Chang, 1966, the glabella is clavate and the preocular sutures diverge forwards. It is doubtful whether Megapalaeolenus should be maintained as an independent genus. Genus PALAEOLENUS Mansuy, 1912 DISCUSSION. The species described below was originally assigned to the genus Schistocephalus Chernysheva, 1956, which has been regarded as a member of the Family Paradoxididae. The distance from the anterior end of the palpebral lobe to the glabella, connected by an eye-ridge, and the presence of a parafrontal band (Fig. 29a), are features of various genera commonly referred to the superfamily Ellipsocephaloidea (Geyer 1990b). The type species of Schisto- cephalus, S. enigmaticus Chernysheva (1956: pl. 30, figs 1,3), has a parallel-sided glabella on which the glabellar furrows S1 to S3 are arched backwards and joined strongly across the mid-line; S4 lies relatively close to S3 and is very short. The anterior part of the glabellar appears transversely oval. Other species of Schistocephalus have been described which show rather diverse glabellar morphol- ogy (Chernysheva 1971: pls 6, 7). Most of them have a slightly clavate glabellar with a semi-circular frontal lobe; some of them, such as S. juvenis Chernysheva, 1956 (Sdzuy 1995: pl. 1, fig. 8) and S. amzassiensis Fedjanina (in Chernysheva 1971: pl. 6, figs 8-13), share with S. enigmaticus the strongly transglabellar furrows S2 and S3. See also S. ex gr. juvenis well figured in Egorova et al. (1976: pls 32-34). In some other early species such as S. antiquus Chernysheva, 1956, and S. tchernyshevae Bognibova (in Chernysheva 1971) these furrows do not join across the glabella. The latter forms are closer in this feature to Palaeolenus (especially species that have been referred to Megapalaeolenus) and it seems appropriate to transfer them to that genus rather than extend Schistocephalus unduly. Chu (1962) suggested that Palaeolenus is ancestral to Schistocephalus. Ferralsia Cobbold (1935) is very similar to Palaeolenus, but Geyer & Elicki (1995: 112), who reviewed Ferralsia, maintained that it could be distinguished from Palaeolenus by its shorter and more regularly spaced glabellar furrows; in at least some species of Palaeolenus S3 and S4 are closer together than S1 and S2. Further- more, Ferralsiatends to have a longer preglabellar field and narrower interocular fixigenae. However, in view of the variation shown by species of Palaeolenus and Schistocephalus, these features, even if they are considered to be of generic value, may be difficult to apply. It is possible that the genus Gigoutella Hupé, 1953, would be an appropriate reference for some of those taxa with discontinuous glabellar furrows, but regrettably the genus is known only from a single schematic line-drawing (which is misleading according to Geyer & Elicki 1995: 112). As attempts to examine the original material have been unsuccessful, the nature and relationships of the only described species, G. atlasensis Hupé (1953), remain to be elucidated, but it may prove to be a senior synonym of Megapalae- olenus (and, following Sdzuy (1995), Schistocephalus if a broad view is taken of that genus), or a junior synonym of Ferralsia. Palaeolenus antiquus (Chernysheva, 1956) Figs 29-38 1956 Schistocephalus antiquus Chernysheva: 150, pl. 30, fig. 6 {cranidium figured, compared with S. enigmaticus]. 1976 = Schistocephalus antiquus Tchernysheva [sic]; Egorova et al.: 74, pl. 23, figs 11-14, pl. 25, figs 1,2, pl. 28, fig. 1 [figures of several cranidia]. 1995 Schistocephalus antiquus Chernysheva; Sdzuy: pl. 1, fig. 9 [new figure of holotype]. NEW MATERIAL. Sixteen cranidia (mostly fragmentary), two librigenae and three small pygidia, all from a calcarenite bed (Fig. 6) in a culvert, 0.8 km N of Wadi Zarga Ma’in (BM It26214—30). DESCRIPTION. Glabella (including occipital ring, LO) clavate, oc- cupies 85% of cranidial length; forward of L2 widens to a maximum opposite S4, where it is about 120% of the width of L1. Glabellar lobes L1 to L4 become progressively shorter (exsag.); the frontal lobe is well rounded anteriorly. LO without node. S1 slightly curved inwards and backwards, with a tendancy to bifurcate medially; S2 approximately transverse but each furrow forms a slight convex curve anteriorly; S3 similar to S2 but extends inwards and slightly forwards; S4 shorter than S3, curved or more anteriorly directed. Anterior border has terrace-lines parallel to margin and is a little longer sagittally than preglabellar field. Preocular section of facial suture diverges forward at about 30° to sagittal line. Palpebral lobe one-third of cephalic length, continuous with eye-ridge which reaches glabella opposite S4 and extends forward into a narrow parafrontal band, seen on some specimens (Figs 29a, 34). Interocular area of fixigena about two-thirds of glabellar width at $1. Postocular area of fixigena not quite as wide as LO. Exterior surface granulose, most coarsely so on the median part of the glabella and the interocular fixigena, more finely on the preocular fixigena. Internal mould almost smooth, very finely pitted, indicating very fine granulation on the parietal surface of the exoskeleton. Librigena narrow, the border occupying nearly half the total width. Genal spine very short (Fig. 36). Pygidium small, with wide short axis having one distinct and one faint axial ring. Pleural field very small with one pleural furrow and two faint interpleural grooves (Fig. 33). DISCUSSION. The specimens from Wadi Zarga Ma ‘in agree closely with the holotype and also the specimens figured by Egorova ef al. (1976), except that the interocular fixigena is a little wider in some of the Jordanian specimens; the glabella widens forward less than in the holotype (Sdzuy 1995: pl. 1, fig. 9), but more than some of the 144 A.W.A. RUSHTON AND J.H. POWELL STRATIGRAPHY AND TRILOBITE FAUNAS FROM THE CAMBRIAN BURJ FORMATION 145 other figured specimens (Egorova et al. 1976: pl. 23, fig. 11, pl. 25, fig. 1). Granulate sculpture is not seen in the holotype but is shown by Egorova et al. (1976: pl. 28, fig. 1). Palaeolenus tchernyshevae (Bognibova in Chernysheva 1971: pl. 7, figs 6, 7, 9-12) differs from P antiquus in having a narrower border and lacking a preglabellar field, so that the glabella occupies well over 90% of the cranidial length. The pygidia assigned to the two species are much alike. Among species described from China the most similar is Palaeolenus fengyangensis Chu, 1962, which has an expanded glabella and divergent preocular sections of the facial suture, and has been referred to Megapalaeolenus. Figured material (Chu 1962; Zhang et al. 1980: pl. 72, figs 6-8) is of smaller cranidia than our material, but the glabella appears proportionately wider, there is a small occipital node and the preocular sutures are less divergent; the surface is not recorded as granulose. HORIZON. Palaeolenus antiquus is recorded from the antiquus Zone at the base of the Amgan Stage in sections on the rivers Lena and Amga in eastern Siberia, and extends into the base of the overlying Kounamkites Zone (Egorova et al. 1976, table, p. 14); it occurs in carbonate deposits, in contrast to such species as_S. amzassensis Fedjanina and S. impressus Fedjanina (both in Chernysheva 1971), which are recorded from clastic deposits (Chernysheva 1971: table, column 1). Species retained in Schistocephalus (S. enigmaticus, S. juvenis) are recorded from higher horizons (Chernysheva 1971). ACKNOWLEDGEMENTS Powell thanks the Director-General of the Natural Resources Authority (N.R.A.), Jordan, and the staff of the Geology Directo- rate, N.R.A., for their support during his involvement with the National 1:50,000 scale Geological Mapping Project. He also acknowledges funding from the Overseas Development Administration (O.D.A.) during his time in Jordan. We thank Mr I. J. Andrews (B.G.S.) and Dr S. G. Molyneux whose critical readings much improved the typescript; Dr G. Geyer for discussion and Ms Claire Mellish (Natural History Museum) for technical assistance. The photographs were taken by H. J. Evans and H. Taylor, and Prof. W. T. Dean kindly supplied the original prints of Figs 21 and 22. Powell publishes by permission of the Director, British Geological Survey (N.E.R.C.). REFERENCES Amireh, B. S., Schneider, W. & Abed, A. M. 1994. Evolving fluvial-transitional- marine deposition through the Cambrian sequence of Jordan. Sedimentary Geology, Amsterdam, 89: 65-90. Andrews, I. J. 1991. Palaeozoic lithostratigraphy in the subsurface of Jordan. Subsur- face Geology Bulletin, no. 2, Geology Directorate, Natural Resources Authority, Amman. 75 pp. Bender, F. 1968. Geological Map of Jordan. Scale 1:250 000 in five sheets. Geological Survey of the Federal Republic of Germany, Hannover. — 1974. Geology of Jordan. 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Figs 29-38 Palaeolenus antiquus (Chernysheva), Wadi Zarqa Ma’ in. 29a—c, top, front and side views of exfoliated cranidium, showing parafrontal band, It.26214, x 4. 30-32, small cranidia showing external surface, x 4; 30, It.26 222; 31, It.26221; 32a, b, top and side views of It.26216. 33, pygidium, It.26228, x 6. 34a, b, latex cast of external mould, oblique and top views, It.26217, x 4. 35, fragmentary cranidium showing sculpture of fixigena, It.26218, x 4. 36, small librigena, It.26226, x 5. 37, fragment of large cranidium, showing glabellar furrows; the internal mould is finely pitted, It.26215, x 4. 38, fragment of cranidium, showing palpebral lobes and postocular facial suture, It.26220, x 4. 146 Mansuy, H. 1912. Etude géologique du Yun-nan oriental. Ie Partie: Paléontologie. Mémoirs du Service géologique de |’ Indochine, Hanoi-Haiphong, 1: 147 pp., 25 pls. Masarwah, R. 1987. Report on borehole GTZ-2D, Zarqa Main area. Geothermal Exploration Project. 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(Geol.) 54(2): 147-154 Issued 26 November 1998 The first Palaeozoic rhytidosteid: Trucheosaurus major (Woodward, 1909) from the Late Permian of Australia, and a reassessment of the Rhytidosteidae (Amphibia, Temnospondyli) CLAUDIA A. MARSICANO Departamento de Ciertias Geologicas, Universidad de Buenos Aires, Ciudad Universitaria Pab. II, 1428 Buenos Aires, Argentina ANNE WARREN School of Zoology, La Trobe University, Bundoora, Victoria 3083, Australia Synopsis. A restudy of Bothriceps major, atemnospondy| from the Late Permian of Australia, has resulted in anew taxonomic assignment of the specimen. The species is returned to Jrucheosaurus and the specimen is recognized as arhytidosteid, rather than abrachyopid. Thus, it constitutes the first Palaeozoic record of the Rhytidosteidae, which has long been considered to be restricted to the Early Triassic. A phylogenetic analysis of all taxa previously included in the superfamily Rhytidosteoidea was performed. One monophyletic group, the family Rhytidosteidae, is recognized, but the relationships of most taxa within that clade remain unresolved. INTRODUCTION In 1909, Woodward described a new Australian brachyopid taxon, Bothriceps major, based on a specimen collected in Late Permian deposits from the Sydney Basin (New South Wales). The genus was previously erected by Huxley (1859) for an Australian brachyopid, B. australis, represented by a single skull of unknown provenance (Watson 1919, 1956; Welles & Estes 1969; Warren 1997). Subse- quently, Watson (1956) restudied B. major and referred the specimen to a new genus of brachyopid, Trucheosaurus, largely because “in the few structures clearly shown in the only known specimen it differs from the type of the genus Bothriceps and indeed from all other known genera of the family’, and also because ‘the specimen is important as showing the occurrence of a typical brachyopid at an early horizon’. Subsequently, Cosgriff (1969) presented a brief redescription of 7. major based on his own observation of part of the type material (MMF 12697), and also discussed the age of the specimen. Welles & Estes (1969) argued that the new genus, Trucheosaurus, could not be justified, so they returned the species to Bothriceps. The holotype material of B. major consists of a poorly preserved specimen which includes the skull and a partial articulated postcranial skeleton. At present, the specimen comprises four pieces distributed in three different repositories: the skull (MMF 12697a) is in the Geological Survey of New South Wales (Sydney), the postcranial skeleton (AMF 50977) in the Australian Museum (Sydney), and the counterpart of both skull and postcranial skeleton (BMNH R3728) in the collections of The Natural History Museum, London. The present paper is a redescription and a reassessment of the taxonomic position of B. major based on a re-evaluation of the entire holotype material. It was prompted during our joint study of the material in 1995 when the Australian part of the skull was further prepared, revealing an extended quadratojugal area on the left hand side. The specimen then assumed a triangular shape, with the © The Natural History Museum, 1998 oe 095.) posterior margin apparently lacking both tabular projections and otic embayment, a morphology found in several members of the family Rhytidosteidae. A few patches of rhytidosteid ornament were also present. Bothriceps major is returned to Watson’s available taxon, Trucheosaurus, and included in the family Rhytidosteidae. A preliminary phylogenetic analysis of the family Rhytidosteidae is presented and the position of the taxon discussed in a cladistic context. SYSTEMATIC PALAEONTOLOGY TEMNOSPONDYLI Zittel, 1888 Family RHYTIDOSTEIDAE Huene, 1920 Genus TRUCHEOSAURUS Watson, 1956 TYPE SPECIES. Bothriceps major Woodward 1909; Late Permian (Dzhulfian), Sydney Basin, New South Wales, Australia. DIAGNOSIS. As for the type and only species. Trucheosaurus major (Woodward 1909) 1909 =Bothriceps major Woodward: 319, pl. LI. 1956 = Trucheosaurus major (Woodward); Watson: 327-330, fig. 3. 1969 Bothriceps major Woodward; Welles & Estes: 22. 1969 Trucheosaurus major (Woodward); Cosgriff: 80. 1972 Trucheosaurus major (Woodward); Howie: 269. 1973 Trucheosaurus major (Woodward); Cosgriff: 1095-1100. 1974 Trucheosaurus major (Woodward); Cosgriff: 94. 1977 Bothriceps major Woodward; Chernin: 88. 1981 Bothriceps major Woodward; Warren: 273. 1997 —Bothriceps major Woodward; Warren: 27, fig. 3. Figs 1-6 148 C.A. MARSICANO AND A. WARREN Fig. 1 Trucheosaurus major, holotype MMF 12697a. Skull. Scale bar represents 20 mm. DIAGNOsIS. Rhytidosteid amphibian apparently lacking tabular projections and otic notch; markedly small orbits located laterally on the anterior third of the skull table; extremely anteroposteriorly elongated parietal bones, which are nearly three times the length of the frontals and apparently without pineal foramen. HOLotyPeE. Skull table (MMF 12697a), the partially complete and articulated postcranial skeleton (AMF 50977), and the counterpart of both skull and postcranial skeleton (BMNH R3728). TYPE LOCALITY AND HORIZON. Glen Davis Formation of the Charbon Subgroup, the lower deltaic facies of the Illawarra Coal Measures, Airly, near Capertee in the west of the Sydney Basin (New South Wales, Australia). The whole of the Illawarra Coal Measures are Late Permian (Young & Laurie 1996). The Glen Davis Forma- tion, which is placed mid-way through the Illawarra Coal Measures (McMinn 1985), contains the palynomorph Microreticulatisporites bitriangularis, the index form for the base of the APP5.2 Interval Zone (Burgeretal. 1992), making it middle Dzhulfian. This Dzhulfian correlation for the middle part of the Illawarra Coal Measures was confirmed in the most recent survey of evidence for the placement of the Permo-Triassic boundary in Australia (Foster et al. 1997). DESCRIPTION Skull. As mentioned above, the specimen is only preserved as a thin layer of bone on two slabs (part and counterpart). Although obvi- ously part and counterpart of the same specimen, the two halves do not meet cleanly when fitted together as several millimetres of the bone is missing in places. Determining sutures was difficult as little detail remains, perhaps because the specimen was preserved in a torbanite. The clearest sutures are in the area of the left tabular, postparietal, supratemporal, parietal, postfrontal and postorbital. The other sutures were deline- ated following the pattern of the bone radiation, although in the anterior snout region sutures remain fairly unclear. Suture lines were traced with chalk on the part and counterpart (Figs 1, 2) and the specimens drawn (Figs 3, 4). The drawings were then superimposed and the skull redrawn as a composite (Fig. 5). The main problem encountered during our restoration was determining the position of the orbits, which have been restored in the only possible place. The nostrils are marked by raised areas. Apparent ornamentation pre- served is faint but seems to show a delicate and smooth spider-web pattern with small nodes on the ridges. The skull table is nearly straight sided, with the posterior margin lacking both tabular projections and otic embayment. The orbits must have been very small, and located laterally on the anterior third of the skull table. There is no sign of a pineal foramen. A striking feature of the specimen is the extremely anteroposteriorly elongated parietal bones, which are nearly three times longer than the frontals. Apparently, there is no lachrymal bone. Part of the occiput is visible behind the posterior border of the TRUCHEOSAURUS MAJOR AND REASSESSMENT OF THE RHYTIDOSTEIDAE 149 Fig. 2 Trucheosaurus major, holotype BMNH R3728. Skull. Scale bar represents 20 mm. skull table, presumably owing to the dorso-ventral compression of the specimen. A slender left paroccipital process is the best pre- served part of the skull. It shows a clear tabular-exoccipital suture close to the area of the exoccipital condyle. Part of the descending portion of the left postparietal is also preserved. Posteriorly to the postparietals, a layer of bone is present and presumably could be either part of the palate (? parasphenoid) or part of the pectoral girdle (? interclavicle). It has been omitted from the figures but can be seen in the photographs (Figs 1, 2). On the posterior left corner of the skull, a fragment of bone projects behind the putative quadratojugal. It either represents part of an extension of the quadratojugal or is part of the mandible. In Fig. 5, we have restored it as a quadratojugal. Postcranial skeleton. Parts of the right fore and hind limb and at least 31 presacral and postsacral centra are preserved, with accom- panying ribs (Fig. 6). The condition of the vertebrae is such that they are most easily counted by means of the clearly defined ribs. In the anterior part of the column the section is frontal, with both left and right ribs from 21 centra preserved. More posteriorly, a flake of torbanite containing 5 ribs is missing from the right side. Following this, the section changes so that it preserves part ribs, only, on the left and seven apparent centra with accompanying neural arches on the right. Next are three structures which resemble swept back neural spines from a tail fin with the final two vertebrae repre- sented by poorly defined centra The column is certainly rhachitomous in the caudal region but could be rhachitomous or stereospondylous more anteriorly. The ribs themselves are shorter than usual for temnospondyls. In the anterior part of the column they are curved but the curvature is not preserved posteriorly. No indication of uncinate processes is present on any rib. The humerus, radius and ulna of the right fore limb are partially preserved close to their expected positon, as are several other small displaced elements. Two long bones either side of the vertebral column in this area may be the remains of a displaced left fore limb or partial pectoral girdle elements. The right hand element was labelled “x” by Woodward (1909). More posteriorly, several patches of bone are preserved on the right and may be the tibia and fibula of both hind limbs as well as some metapodials. There is no sign of the femora. Fig. 3 Trucheosaurus major, holotype MMF 12697a. Diagram of skull from Fig. 1. Scale bar represents 20 mm. m?, possible mandibular fragment. Fig.4 9 Trucheosaurus major, holotype BMNH R3728. Diagram of skull from Fig. 2. Scale bar represents 20 mm. C.A. MARSICANO AND A. WARREN Fig.5 = Trucheosaurus major. Drawing of the skull incorporating only those parts preserved on MMF 12697 and BMNH R3728. No attempt has been made to correct probable flattening of the skull or to speculate on the original shape of the occiput. It is unlikely that the paroccipital process of the tabular and exoccipital protrudes posteriorly in the undistorted specimen. Scale bar represents 20 mm. f, frontal; j, jugal; mx, maxilla; n, nasal; p, parietal; pf, prefrontal; pmx, premaxilla; po, postorbital; pof, postfrontal; pp, postparietal; qj, quadratojugal; sq, squamosal; st, supratemporal; t, tabular. PHYLOGENETIC ANALYSIS The family Rhytidosteidae was erected by Huene (1920) for Rhytidosteus and Peltostega. Later, Cosgriff (1965) created the superfamily Rhytidosteoidea for the Rhytidosteidae and the monogeneric family Laidleridae (Kitching 1957). Subsequently, Cosgriff & Zawiskie (1979) removed the Laidleridae and erected a new rhytidosteid family, the Indobrachyopidae, for those members of the Rhytidosteidae with rounded, as opposed to triangular, skulls. Because they were unable to distinguish the families Rhytidosteidae and Indobrachyopidae except on the basis of skull outline, Warren & Black (1985) returned the members of the Indobrachyopidae to the Rhytidosteidae. Shishkin (1994) re-erected the Rhytidosteoidea, including in it the Rhytidosteidae and Peltostegidae. More recently, Warren (1998) restricted the superfamily to the Rhytidosteidae and Laidleridae. The purpose of this preliminary analysis is to provide a hypothesis for the relationships among rhytidosteids and determine whether more than one monophyletic group is represented. Nearly all those characters used in the different revisions mentioned above were considered. Nevertheless, the triangular shape of the skull, although it was used in all previous diagnoses of the family, was not included as it was not possible to define discrete states for this character, especially in the case of incomplete material. The following rhytidosteid taxa were used in the analysis: Rhytidosteus capensis (Owen 1884, Cosgriff 1965), Peltostega sp. (Nilsson 1946), Laidleria gracilis (Kitching 1957, Warren 1998), Indobrachyops panchetensis (Heune & Sahni 1958, Cosgriff & Zawiskie 1979), Deltasaurus kimberleyensis (Cosgriff 1965), Rewana quadricuneata (Howie 1972), Derwentia warreni (Cosgriff 1974), Arcadia myriadens (Warren & Black 1985), Boreopelta vavilovi (Shishkin & Vavilov 1985), Mahavisaurus sp. (Lehman 151 Fig. 6 Trucheosaurus major, holotype AMF 50977. Postcranial skeleton. Scale bar represents 50 mm. 152 1966, Cosgriff & Zawiskie 1979), Pneumatostega potamia (Cosgriff & Zawiskie 1979), Acerastea wadeae (Warren & Hutchinson 1987) and Trucheosaurus major. The lydekkerinid taxa Lydekkerina (Parrington 1948) and Chomatobatrachus (Cosgriff 1974) and the family Trimerorhachidae (Broom 1913, Olson 1955) were consid- ered as outgroups, taking into account previous cladistic analyses of the Temnospondyli (Milner 1990, 1991). All terminal taxa used in the analysis were examined by one or both of the authors. The taxon- character state matrix (Table 1) and character list are included in the Appendix. DISCUSSION. The incorporation in the analysis of several taxa represented by poorly preserved specimens greatly increased the instability of the resultant cladogram, and thus the number of equally parsimonious trees. Under these circumstances, four taxa were excluded from the analysis, reducing the number of terminals to twelve. Taxa excluded were: Mahavisaurus sp., Pneumatostega potamia, Acerastea wadeae and Trucheosaurus major, and their relationships are discussed separately. Accordingly, the phylogenetic results are based on an analysis of 18 characters and 12 terminal taxa, using Swofford’s (1993) PAUP 3.1. The branch-and-bound search algorithm resulted in 51 equally-parsimonious trees with a tree length of 23 steps (CI = 0.83 and RI = 0.89). Fig. 7 depicts the strict consensus tree, showing the consistent nodes among the 51 trees. The monophyletic group (ndobrachyops + (Boreopelta + Derwentia + Laidleria + Peltostega + (Rhytidosteus + Deltasaurus) + Rewana + Arcadia)), that we consider the family Rhytidosteidae (Fig. 7, node 1), is supported by the following eight unequivocal syn- apomorphies: orbits located close to the skull margin (1); otic notch reduced or absent (3); tabular horns reduced or absent (4); straight posterior margin of the palate (7); otic flange absent (8); ‘pockets’ on the parasphenoid absent (11); cultriform process of the para- sphenoid broad and flat (14) and exoccipital condyles horizontally elongated (16). Two further derived character states of this clade are: the presence of a ‘twisted’ quadrate ramus of the pterygoid (10), and a reduced palatal tooth row (17), although the former reverses in Derwentia and the latter reverses in Peltostega and Laidleria. The derived condition of character 18 (presence of shagreen on all bones of the palatal series) has long been used as a diagnostic family C.A. MARSICANO AND A. WARREN character (Cosgriff & Zawiskie 1979, Warren & Black 1985, Warren & Hutchinson 1987, Shishkin 1994). In the present analysis, this derived character state justifies a more inclusive group which includes the Tasmanian ‘lydekkerinid’ Chomatobatrachus. Moreover, among rhytidosteids, the shagreen is reduced in Derwentia and apparently absent in Laidleria. The condition present in Indobrachyops for characters 7, 8 and 16 is unknown, and their derived states might justify a less inclusive group excluding Indobrachyops. Within Rhytidosteidae, Indobrachyops is the sister group of an unresolved clade which includes all the remaining rhytidosteid taxa: (Boreopelta + Derwentia + Laidleria + Peltostega + (Rhytidosteus + Deltasaurus ) + (Rewana + Arcadia)) (Fig. 7, node 2). This monophyletic group is justified by two unequivocal derived character states: skull sculpture with nodules or pustules (5) and lachrymal bone absent (6), although the condition present in Boreopelta and Peltostega for the latter is unknown. Another synapomorphy of this clade is equivocal: the condition of a contact between the palatine and vomer lateral to the choana (15), which is unknown in Rewana, Boreopelta and Peltostega, and reverses in Derwentia and Arcadia. Within the clade, the sister-taxon relationship between the South African Rhytidosteus and the Australian Deltasaurus (Fig. 7, node 3) is justified by the derived condition of characters 12 (exoccipital-pterygoid suture visible in palatal view) and 17 (palatal tooth row absent). Also, the Australian taxa Rewana and Arcadia form a clade (Fig. 7, node 4), justified by the presence of a strikingly low ascending ramus of the pterygoid (9) and the presence of the quadrate condyles well behind the occipital ones (13). It is important to remark that the Australian taxa Arcadia, Rewana and Derwentia share the derived condition of character 2 (the orbits in the anterior half of the skull table); however, as the presence of this condition is unknown in some of the members of the in-group (Boreopelta and Peltostega), it appears in the analy- sis as an equivocal synapomorphy of the (Rewana + Arcadia) clade. Although not included in the analysis, the taxa Mahavisaurus, Pneumatostega, Acerastea and Trucheosaurus are considered rhytidosteids and in a more derived position than Indobrachyops. This position is supported by the presence in those taxa of a skull sculpture with nodules or pustules, and the absence of lachrymal bones. BothAcerastea and Trucheosaurus appear to be more closely related to the other Australian taxa through the presence of the orbits in the anterior half of the skull, a condition especially marked in © @ \y SF Om cS KF S QS ON 0 \) S eS x wr ww ww Ee SOE RS SSS SC SC SS SS © S © Or OO 9 CORO Ce Se Oe ee es we Be Oe WS OR PS DS Fig. 7 Strict consensus cladogram of 51 equally parsimonious trees. TRUCHEOSAURUS MAJOR AND REASSESSMENT OF THE RHYTIDOSTEIDAE 153 Trucheosaurus, and the position of the quadrate condyles behind the occipital ones, visible only in Acerastea. The lack of resolution of most of the generic relationships in the analysis performed herein is apparently due to both the low number of informative characters and the amount of missing entries, which contribute substantially to the instability and poor resolution of the resultant cladogram (Novacek 1992). This result reflects the lack of consensus among investigators concerning the taxonomic validity and content of Rhytidosteoidea and its included families, a problem which has been debated over the last thirty years (see above). This situation strongly indicates that a redescription and further prepara- tion of some specimens is needed, and in many cases the discovery of new, more complete material would improve the resolution of the analysis. Nevertheless, and as a result of the present analysis, most of the Australian taxa (Arcadia, Rewana, Acerastea, Trucheosaurus, and Derwentia) appear more closely related than they are to other members of the family. The only exception is the Australian taxon Deltasaurus, which appears as the sister-taxon of Rhytidosteus, from the South African Karoo. The fact that Trucheosaurus is considered here to be arhytidosteid taxon rather than a brachyopid, constitutes the first Palaeozoic record of Rhytidosteidae, a family which has long been considered to be restricted to the Early Triassic (Scythian) and because of this used in a biostratigraphic sense (Cosgriff 1969, 1984; Shishkin 1994). Conversely, Brachyopidae no longer has a Permian repre- sentative and is thus restricted to the Mesozoic. A second brachyopid, Bothriceps australis, was considered to be Permian but only because of its taxonomic relationship with Trucheosaurus major, and 1s most likely Triassic (Warren 1997). When a phylogenetic hypothesis is combined with the observed fossil record of the terminal taxa, stratigraphic separation between sister-taxa demands substantial range extensions beyond those pre- dicted by the observed stratigraphic record (“ghost lineages’ of Norell 1992). Thus, the age of Trucheosaurus and its position on the cladogram extend the rhytidosteid diversification and preceding nodes into the Late Permian. Equally, if a more inclusive cladistic analysis of temnospondyls is considered (e.g. Milner 1990), the resultant calibrated phylogeny (Norell 1992) suggests that the phyletic diversification of Mesozoic temnospondyls (‘stereospondyls’) oc- curred earlier than indicated by the fossil record. The implication is that the apparent radiation of taxa in the Early Triassic was an extension of a Late Permian event, which probably took place in Gondwana as the earliest and most diverse of the Triassic temnospondyls faunas occur in that area. Therefore, the seeming abruptness of the Permo-Triassic temnospondyl turnover (Milner, 1990: fig. 15.3) might be both an effect of the lack of recent revisons of the known temnospondy] record and its interpretation relative to testable phylogenetic patterns, and a taphonomic artifact. The taphonomic effect may result from the absence of preserved temnospondyl-bearing sequences in the Late Permian, or the preser- vation of fauna from selected sequences only, as appears to have been the case in South Africa. ACKNOWLEDGEMENTS. We are grateful to the following for the loan of material: Dr Angela Milner of The Natural History Museum, London, Mr Robert Jones of the Australian Museum, Sydney, and Dr John Pickett and Dr Ian Percival of the Geological Survey of New South Wales, Sydney. Professor Michael Shishkin of the Paleontological Istitute, Moscow, confirmed some of our interpretations of the sutures on the skull roof. Comments on an earlier version of the manuscript by Dr. Ana Maria Baez of the Universidad de Buenos Aires, Buenos Aires, and Dr. Andrew Milner of Birkbeck College, London, greatly improved its content. The photographs were taken by the La Trobe University Photographic Unit. The work was supported by an Austral- ian Department of Industry and Commerce Grant to both authors and an Australian Research Council Grant to A. Warren. REFERENCES Burger, D., Foster, C. B. & McKellar, J.T. 1992. A review of Permian to Cretaceous palynostratigraphy in Eastern Australia. Records of the Bureau of Mineral Re- sources, Geology and Geophysiscs, Canberra, 1992 (5): 1-26. Chernin, S. 1977. A new brachyopid, Batrachosuchus concordi sp. noy. from the Upper Luangwa Valley, Zambia with a redescription of Batrachosuchus browni Broom, 1903. Palaeontologia Africana, Johannesburg, 20: 87-109. Cosgriff, J. W. 1965. A new genus of Temnospondyli from the Triassic of Western Australia. Journal of the Royal Society of Western Australia, Perth, 48: 65-90. 1969. Blinasaurus, a brachyopid genus from Western Australia and New South Wales. Journal of the Royal Society of Western Australia, Perth, 52 (3): 65-88. 1973. Notobrachyops picketti, a brachyopid from the Ashfield Shale, Wianamatta Group, New South Wales. Journal of Paleontology, 47 (6): 1094-1101. 1974. The Lower Triassic Temnospondyli of Tasmania. Geological Society of America Special Paper, Boulder, 149: 1-134. 1984. The temnospondy] labyrinthodonts of the earliest Triassic. Journal of Vertebrate Paleontology, Lawrence, 4: 30-46. & Zawiskie, J. M. 1979. A new species of the Rhytidosteidae from the Lystrosaurus Zone and a review of the Rhytidosteoidea. Palaeontologia Africana, Johannesburg, 22: 1-27. Foster, C. B., Logan, G. A., Summons, R. E., Gorter, J. D. & Edwards, D. S. 1997. Carbon isotopes, kerogen types and the Permian-Triassic boundary in Australia: implications for exploration. APPEA Journal, Canberra, 1997: 472-489. Howie, A. A. 1972a. On a Queensland labyrinthodont. Jn K.A. Joysey and T.S. Kemp (Eds.) Studies in Vertebrate Evolution, pp. 51-54. Oliver and Boyd, Edinburgh. 1972b. A brachyopid labyrinthodont from the Lower Trias of Queensland. Proceedings of the Linnean Society of New South Wales, Sydney, 96 (4): 268-277. Huene, F. yon 1920. Gonioglyptus, ein Alttriassischer Stegocephale aus Indien. Acta Zoologica, Stokholm, 1: 433-464. — & Sahni M. R. 1958. Indobrachyops panchetensis gen. et sp. nov. from the Upper Panchets (Lower Trias) of the Raniganj Coalfield. Monographs of the Paleontological Society of India, Calcutta, 2: 1-24. Huxley, T. H. 1859. On some amphibian and reptilian remains from South Africa and Australia. Quarterly Journal of the Geological Society, London, 15: 642-658. Kitching J. W. 1957. A new small stereospondylous labyrinthodont from the Triassic beds of South Africa. Palaeontologia Africana, Johannesburg, 5: 67-82. Lehman J. P. 1966. Nouveaux Stégocephales de Madagascar. Annales de Paléontologie (Vertébrés), Paris, 52: 117-139 McMinn, 1985. Palynostratigraphy of the Middle Permian coal sequences of the Sydney Basin. Australian Journal of Earth Sciences, Melbourne, 32: 301-309. Milner, A. R. 1990. The radiations of temnospondyl amphibians. /n, Taylor, P.D. & Larwood G.D. (editors). Major Evolutionary Radiations. Systematics Association, Special Volume 42: 321-349. 1991. Lydekkerinid temnospondyls. Relationships and ‘extinction’. /n, Kielan- Jaworowska, Z., Heintz, N. & Nakrem, H. (editors). V Symposium on Mesozoic Terrestrial Ecosystems and Biota. Extended Abstracts, Contribution from the Paleontological Museum, University of Oslo, pp. 49-50. Nilsson, T. 1946. On the genus Pe/fostega Wiman and the classification of the Triassic stegocephalians. Svenska Vetenskapsakademiens Handlingar, Stokholm, 23: 3-55. Norell, M. 1992. Taxic origin and temporal diversity: the effect of phylogeny. /n, Novacek, M.J. & Wheeler, Q.D. (editors). Extinction and Phylogeny, pp.89-118. Columbia University Press, New York. Novacek, M. 1992. Fossil topologies, missing data and the higher level phylogeny of eutherian mammals. Systematic Biology, Lawrence, 41: 58-73. Shishkin, M. A. 1994. A Gondwanan rhytidosteid (Amphibia, Temnospondyli) from the Lower Triassic of southern Cisuralia. Paleontological Journal, New York, 28: 127-143. & Vavilov, M. H. 1985. New rhytidosteid (Amphibia, Labyrinthodontia) from the Russian Triassic. Doklady Academia Nauk CCCP, Moscow, 282: 971-975. Swofford, D. L. 1993. PAUP: Phylogenetic Analysis Using Parsimony, version 3.1. Computer program distributed by the Illinois Natural History Survey, Champaign, Illinois. Warren, A.A. 1981.A horned member of the labyrinthodont superfamily Brachyopoidea from the Early Triassic of Queensland. Alcheringa, 5: 273-288. —— 1997. A tetrapod fauna from the Permian of the Sydney Basin. Records of the Australian Museum, Sydney, 49: 25—33. — (1998). Laidleria uncovered: a redescription of Laidleria gracilis Kitching (1957), a temnospondyl from the Cynognathus Zone of South Africa. Zoological Journal of the Linnean Society, London, 122: 167-185. 154 Warren, A. A. & Black, T. 1985. A new rhytidosteid (Amphibia, Labyrinthodontia) from the Early Triassic Arcadia Formation of Queensland, Australia, and the rela- tionships of Triassic Temnospondyls. Journal of Vertebrate Paleontology, Lawrence, 5: 303-327. — & Hutchinson, M. N. 1987. The skeleton of a new hornless rhytidosteid (Amphibia, Temnospondyli). Alcheringa, Sydney, 11: 291-302. Watson, D. M. S. 1919. The structure, evolution and origin of the Amphibia. The ‘Orders’ Rachitomi and Stereospondyli. Philosophical Transactions of the Royal Society of London (B), London, 209: 1-73. 1956. The brachyopid labyrinthodonts. Bulletin of the British Museum of Natural History (Geology), London, 2: 317-391. APPENDIX Character List for Table 1 1. Position of the orbits I. The position of the orbits in relation to the skull margins: close to the skull midline (0); close to the skull margin (1). Position of the orbits II. The position of the orbits in relation to the skull table length: approximately in the middle (0); in the anterior half of the skull table (1). 3. Otic notch: incised (0); reduced or absent (1). 4. Tabular horns: well developed and posteriorly projected (0); reduced to a broad based triangle or absent (1). 5. Sculpture: ‘normal’ ridge-grooved pattern without pustules or nodules on the junctions (0); spider-web pattern with nodules or pustules on the junctions (Cosgriff & Zawiskie 1979) (1). 6. Lacrimal bone and lacrimal flexure of infraorbital sensory canal: present (0); absent (1). 7. Posterior margin of the palate embayed (0); almost straight (1). Pterygoid otic flange (= oblique ridge): present (0); absent (1). 9. Pterygoid ascending ramus. In those pterygoids without an otic flange, the ascending ramus is a thin lamina that runs along in) gS) C.A. MARSICANO AND A. WARREN Welles, S. P. & Estes, R. 1969. Hadrokkosaurus bradyi from the Upper Moenkopi Formation of Northern Arizona. University of California Publications in Geological Sciences, Berkeley, 84: 1-61. Woodward, A. S. 1909. On a new labyrinthodont from oil shale, at Airly, New South Wales. Records of the Geological Survey of New South Wales, Sydney, 8: 317— 319. Young, G. C. & Laurie, J. R. 1996. An Australian Phanerozoic Timescale. Oxford University Press, Melbourne, 279 pp. von Zittel, K. A. 1888. Handbuch der Palaontologie Abteilung 1. Palaozoologie Band Ill. Vertebrata (Pisces, Amphibia, Reptilia, Aves). R. Oldenbourg, Miinich and Leipzig, 900 pp. the dorsal surface of the quadrate ramus of the pterygoid and across the corpus: extremely low (1); not extremely low (2). Pterygoid quadrate ramus: evenly curved from the horizontal to the vertical plane throughout its length (0); horizontally oriented proximally and vertically oriented distally so it ap- pears twisted (1). 11. Ventral depressions on the parasphenoid corpus (“pockets’ of Watson 1962): present (0); absent (1). 12. Exoccipital-pterygoid suture: not visible in palatal view (0); visible in palatal view (1). 13. Quadrate condyles: well behind the occipital condyles (0); in the same transverse line as the occipital condyles (1). Cultriform process of the parasphenoid: narrow (0); broad and flat (1). 15. Vomer-palatine contact external to the choana so the maxilla is excluded from its border: absent (0); present (1). 10. 16. Exoccipital condyle articular surface: rounded (0); oval and horizontally elongated (1). 17. Palatine tooth row: continuous over the palatine series (0); reduced, so it is only partially present on some of the palatal bones (1); absent (2). 18. Shagreen: reduced so it appears on some of the palatal series only, not including the tooth bearing bones (0); on the palatal series including the tooth bearing bones (1). Table1 Taxon-Character state matrix. The matrix includes 12 taxa and 18 characters. Data missing as a result of lack of preservation or because the state is unknown is coded as “?’, Data unknown but as a result of transformation is coded as ‘“—’. The data matrix was subjected to parsimony analysis using PAUP branch-and- bound option. CHARACTERS Trimerorhachidae Lydekkerina Chomatobatrachus Rhytidosteus Peltostega Laidleria Indobrachyops Deltasaurus Rewana Derwentia Arcadia Boreopelta a a) ~wrRerPrPoocootyoo°cn]me ) a a a a) Re Dae FP Orr F COO = OS OS OS SS Cn ee a a>) Se a ao) NrRNF NY YVYNNSY ! PR OR VRP RRP YD OOCOO a a i) o4yvonryrroocoorceco Le a el oo el el el =) ao) VOOVR OR WRK COCO le a> ee) IR RP REN DNOCO RBPrRORrRrFP RFP ONWr RFR OO Bull. nat. Hist. Mus. Lond. (Geol.) 54(2): 155-163 Issued 26 November 1998 The rhynchonellide brachiopod [sopoma Torley and its distribution M. MOHANTI Department of Geology, Utkal University, Vani Vihar, Bhubaneswar-751004 (Orissa), India C.H.C. BRUNTON Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD Synopsis. The Devonian rhynchonellid brachiopod genus /sopoma Torley, 1934, is described, with comments on species recorded from various geographic regions. /sopoma maymyoensis sp. nov. is erected for some specimens from the Late Eifelian to Early Givetian Padaukpin beds of Burma. /sopoma is mainly Eifelian to Givetian, Middle Devonian, in age. There are two species in the Pragian and Emsian, Lower Devonian, but possible occurrences in the Frasnian, Upper Devonian, have yet to be proved. Biogeographically the genus belongs to the Rhenish-Bohemian Region of the Old World Realm and has Rhenish affinities. INTRODUCTION Having discovered specimens of /sopoma Torley, 1934, incorrectly identified, we determined to investigate this poorly known genus to determine its stratigraphic and biogeographic distribution. One of us had previously identified the genus in north Spain (Mohanti, 1972) and, while investigating that fauna, studied specimens of Jsopoma from various localities in Germany housed at the Senckenberg Natural History Museum at Frankfurt. MATERIAL We have studied specimens representing /sopoma brachyptyctum (Schnur), /. gryps Schmidt, I. orthoglossa (Torley), I. ? ren Schmidt, and J. xestum Torley from the Devonian of Germany, as indicated under the species descriptions. We have also studied specimens in the collections of the Natural History Museum, London, including specimens of Rhynchonella? lummatoniensis Davidson, 1865, which we assign to Jsopoma and for which a lectotype is selected, and the collections from Burma figured and described by Anderson, Boucot & Johnson (1969). Some specimens in this collection identified as Uncinulus subsignata (Reed), are described here as J/sopoma maymyoensis sp. nov. Mohanti also studied [sopoma hertae from the Cantabrian Mountains, Spain, housed in the National Natural History Museum, Leiden, Netherlands, which he had described in 1972. Our comments on other species of /sopoma are based largely upon information from the literature. SYSTEMATIC DESCRIPTIONS Most of the material described here is housed in the BMNH collec- tions of The Natural History Museum, London, and these have registration numbers prefixed by B, BB, or BD. Register numbers of specimens in the Forschungsinstitut Senckenberg, Frankfurt, Ger- many, have the prefix SMF. © The Natural History Museum, 1998 eee 210 \ | Order RHYNCHONELLIDA Kuhn, 1949 Superfamily PUGNACOIDEA Rzhonsnitskaya, 1956 Family ASEPTIRHYNCHIIDAE Savage, 1996 DIAGNOSIS. Pugnacoidea lacking dental plates, dorsal median septum or septalium; fold and sulcus developed anteriorly. DISCUSSION. Savage (1996) introduced the family Asepti- rchynchiidae, which included Aseptirhynchia Soja, 1988, Brunni- rhyncha Havliéek, 1979, Carolirhynchia Havliéek, 1992; Chalimia Baranoy, 1978 and/sopoma Torley, 1934. Xu Han-kui and Yao Zhao- kui (1984: 561, table 3) described a new family, the Katuniidae, in which they placed/sopoma Torley, 1934. Savage (1996), in his major revision of Palaeozoic rhynchonellides, placed Katunia with weak dental plates in the Leiorhynchinae, while Jsopoma was assigned to the new family, the Aseptirhynchiidae, which lacks both dental plates and a dorsal median septum. Genera in the family are united by their similar external morphologies, ie. their posterior smooth shells, anda tendency towards the anterior development of a fold and sulcus in which a few ribs developed. In some, weak additional ribs occur flanking the sulcus. The genera are differentiated principally on their internal characters. In two, Chilimia and Aseptirhynchia, dental plates are either weakly present or developed only in early ontogeny. Shell wall thickening is variable: in Chilimia the walls appear to be thin (Baranoy, 1978: text—fig. 1); in Aseptirhynchia the ventral valve walls became thickened and overgrow the juvenile dental plates, but the dorsal valve remains relatively thin; in /sopoma both valves became thickened, but the hinge plates remain free, and the teeth and sockets are particularly strongly developed; in Carolirhynchia and Brunnirhyncha the valve wall thickening fused the hinge plates to the dorsal interior, leaving only a groove between the median edges. A further distinction in Chilimia is that the hinge plates only became medially disjunct at their anterior extremities. DISTRIBUTION. Aseptirhynchia occurs in the Emsian of Alaska. Carolirhynchia was reported originally from Pragian and Emsian beds in the Barrandian area of Bohemia, although Savage (1996) reported the genus as restricted to the Eifelian. Chilimia is reported from the Middle Devonian of northeast Russia. /sopoma was origi- nally described from the Middle Devonian of Germany, but is fully described below. Brunnirhyncha is of Early Famennian age from the Bruno area of the Czech Republic. Genus ISOPOMA Torley, 1934 TYPE SPECIES. designation. Terebratula brachyptycta Schnur 1853, by original DIAGNOsIS. Aseptirhynchid lacking adult dental plates, with dor- sal valve thickening confined umbonally and free, disjunct hinge plates extending from well-developed inner socket ridges. Ventral valve thick-walled with prominent teeth. There are no median septa in either valve. COMMENT. Below we describe or comment on the twelve species described as belonging to /sopoma, including one new species. The name I. brachyptyctum has been used in Germany to include speci- mens resembling the lectotype of Schmidt (1941), which are longer than wide, as well as more equidimensional specimens commonly found in the Middle and Upper Givetian strata, typically to the east of the river Rhine, Germany. We provide here some sections taken from both forms but have insufficient information to be able to differentiate these forms clearly, other than by their exteriors. Other species, eg. 1. orthoglossa (Torley) and J. ovale Xian & Jian, somewhat resemble the wide forms of I. brachyptyctum and are of similar age. Further studies of these faunas are required to resolve these taxonomical problems and the stratigraphical range of true J. brachyptyctum. SHELL STRUCTURE. The shell structure of Isopoma (Figs 19-21) is poorly known; no primary layer has been seen in fresh condition, but the secondary fibres are relatively large and angular; being some- what rhomboidal in section. This is characteristic of many Palaeozoic rhynchonellids. Isopoma brachyptyctum (Schnur, 1853) Figs 1-5, 19 1853 Terebratula brachyptycta Schnur: 178: pl. 23, fig. 6. 1934 JIsopoma brachyptyctum (Schnur); Torley: 81, pl. 3, figs 12-15. Figs 1,2 /sopoma brachyptyctum (Schnur). 1, syntype; copy of Schnur, 1853: pl. 23, fig. 6; presumed from Eifelian limestone, Blankenheim, Germany; Schnur Collection, Geol.-Palaontological Institute, Bonn; x 2. 2, lectotype; a syntype from the Schnur Collection resembling that of Fig. 1; copy of Schmidt 1941: pl. 4, fig. 88; locality unspecified, but possibly Ahrdorf Formation, Eifelian, Germany; x 2. Both specimens are illustrated in dorsal, anterior and ventral views, but note that Schmidt illustrated the anterior view with the ventral valve uppermost. M. MOHANTI AND C.H.C. BRUNTON 3c 3d Fig. 3. /sopoma brachyptyctum (Schnur). Dorsal, ventral, anterior and lateral views; Givetian Massenkalk, Bilveringsen, Germany; BD 12784, x3, 1941 Isopoma brachyptyctum (Schnur); Schmidt: 45, pl. 4, fig. 88. 1966 —Isopoma brachyptyctum (Schnur); Biernat: 106, pl. 22, figs 1-9. TYPE SPECIMEN. The lectotype, selected by Schmidt (1941: 45, pl. 4, fig. 88), is from Im Kalk zu Blankenheim (Schnur, 1853: 178). Schmidt did not specify the precise stratigraphical level of this specimen, which is in the Schnur Collection at the Geol.- Palaontological Institute, Bonn, Germany. However, the lectotype possibly came from the Ahrdorf Formation (Mohanti, 1972: 170), which is considered to be Middle Eifelian in age (see Paulus, Struve & Wolfart, 1963: 466, text—fig. 1). DIAGNOSIS. Outline approximately equidimensional, with great- est width at about two-thirds of the length of the shell; ventral sulcation prominent, commonly containing two ribs and an addi- tional pair of ribs lateral to the sulcus; fold weakly developed. MATERIAL. German specimens from the Eifel region are: 3 speci- mens (SMF XVII 342b, XVII 342c and XVII Bi) from Bilveringsen; one specimen (SMF XVII 1168a) from Schleddenhof; one specimen (SMF XVII 342k) from the Ahrdorf Formation at Gees; and 5 specimens (SMF XVII 2420) from the Ahbach Formation at Hallert. In addition, unregistered specimens were kindly donated by the late Dr Struve from the upper part of the Lahr Member of the Ahbach Formation (Loc. St. 949) (BD12782—83) and from the Massenkalk (Kohlenstein Member) of the Kohlenstein quarry at Iserlohn- Bilveringsen (BD 12784). STRATIGRAPHICAL RANGE. According to Schmidt (1941: 45), in the Eifel area of Germany /sopoma brachyptyctum ranges from Middle Eifelian (Ahrdorf Formation) to the Fleringen Schichten, which is now known to range from the Ahbach Formation (upper- most Eifelian) to the Curten Formation (Lower Givetian) (Paulus, Struve & Wolfart, 1963: 466, text—fig. 1). The species is also known to the east of the Rhine river in Germany. Torley (1934) described Isopoma brachyptyctum (Schnur) from the Massenkalk (Upper Givetian) of Bilveringsen, near Iserlohn. Schmidt (1951) also briefly remarked upon a specimen of Jsopoma brachyptyctum from the Upper Givetian Flinz kalk of Schleddenhof, near Iserlohn-Letmathe on the east side of the Rhine. RHYNCHONELLIDE BRACHIOPOD JSOPOMA TORLEY 157 Figs 4,5 Jsopoma brachyptyctum (Schnur). 4, section of a dorsal valve at the socket showing well defined, separated, outer hinge plates and crural bases; Ahbach Formation, Lahr Member, mid-Eifelian, Im Lahr, NE of Niederehe, St. 949, Germany; BD 12782, x 9. 5a, b, sections through a shell near the socket, where the valve is thickened, slightly posterior and dorsal to that of Fig. 4; Massenkalk, Kohlenstein Member, Upper Givetian, Iserlohn- Bilveringsen, Germany; BD 12783, x 9. Maillieux (1941: 10) listed Zsopoma aptyctum (Schnur) and I. brachyptyctum from Frasnien (F, beds) in the Devonian of Ardenne, Belgium, but gave no description or illustrations, so the validity of these occurrences cannot be verified. Havlicek (1951, 1961) reported I. brachyptyctum (Schnur) from the Middle Devonian (Givetian) limestones in the vicinity of Celechovice (Moravia). Biernat (1966) described specimens of J. brachyptyctum (Schnur) from the Skaly Beds and one from the Pokrzywianka beds, Holy Cross Mountains, Poland. Although there is some difficulty about the Eifelian/Givetian age for the Skaly Beds, Biernat (1966) thought them to be Lower Givetian on the basis of her brachiopod study. Bublichenko (1974: 72, 73, pl. 10, figs 8-10) described and illustrated [. brachyptyctum (Schnur) from the Krjukovo Beds (Lower? Emsian) of the Russian Rudnogo Altai region. However, serial sections and precise information about the interior is lacking, so the identification is doubtful. Sapel’nikov & Mizens (1984: 23-24, pl. 4, figs 10, 13, pl. 5, figs 4, 5) described and figured I. aff. brachyptyctum (Schnur) from beds with Ivdelinia acutolobata of Lower Givetian age from the central part of the Ufa Amphitheatre in the southwest Urals, Russia. Mamedov (1985) reported the occurrence of Isopoma brachyptycta in a key section of the Middle Devonian of Transcaucasia, in the upper Arpachaisk sub-suite of Givetian age. He claimed that this interval corresponds with the Alchedatskii horizon of the Kuznetsk Basin, the upper parts of the Starooskolskii (old Oskolskii) horizon (Mulinskii/Moulins beds) on the Russian platform and possibly the upper parts of the Aidarlinskii horizon of Kazakhstan. According to Mamedov (1985: 159) the Mont-Aur Layers with Hexagonaria guadrigemina in the Ardennes correspond to this interval and the Bolsdorf layers in the Eifel are possibly synchronous. Sapel’nikov & Mizens (1985), while providing new data on the biostratigraphy of the Ural Mountains, recorded Isopoma aff. brachyptyctum on both western and eastern slopes, at a stratigraphic level which they correlated with the Eifelian-Givetian horizons of the Ardennes-Rhine region of Western Europe. Xian Si-yan & Jiang Zong-long (1978: 289, pl. 106, fig. 14) described and illustrated 1. brachyptyctum (Schnur) from the lower part of the Dushan Formation (Givetian), Dongyao, Xiasi, Dushan County, Guizhou, China. Although no internal information was given, the shape resembles that of the lectotype figured by Schmidt (1941: 45, pl. 4, fig. 88). Xian & Jiang (1978) did not give detailed information on the stratigraphic levels from which their two species (I. brachyptyctum and I. ovale) were found. Isopoma alecto (Barrande, 1847) 1847 Terebratula alecto Barrande: 42, pl. 20, fig. 2. 1961 = Isopoma alecto (Barrande); Havlicek: 40, pl. 6, fig. 5. COMMENT. This species was described from the Pragian of Bohe- mia. Haylicek’s (1961) redescription showed that it is characterized by a ventral sulcus starting just before half the valve length and containing three ribs. Havli¢ek (1961: 40, text-fig. 7) also gave a section showing a thin divided hinge plate and crural bases, which are directed dorsally, as in all known Jsopoma species. Havlicek (1992: 56, table 1) listed this species in the Suchomasty Limestones (Dalejan). The species name was used by Perry (1984) for speci- mens from the Upper Lochkovian of the Yukon Territory in Arctic Canada. However, we think more critical studies are necessary before accepting the Yukon forms as true Jsopoma. Isopoma gryps Schmidt, 1965 Fig. 6 1965 Isopoma gryps Schmidt: 13-16, text-figs 18, 19; pl. 1, figs 1-7. MATERIAL. From Greifenstein, Eifel region, Germany, 17 speci- mens (SMF 19531) and two unregistered specimens, donated by the late Dr Struve, from an exploration trench from the Greifensteinkalk of the same area (BD 12786-87). COMMENT. This species was originally described from the Lower Eifelian Greifensteiner Kalk of the Eifel region. It is characterized by a prominent ventral sulcus, which originates close to the umbo. In some specimens the sulcus contains a single median rib. Serial sections (Fig. 6a—c) show characters typical of the genus, with a thickened dorsal umbo and prominent teeth. Figs 7, 8 1972 Isopoma hertae Mohanti: 170, pl. 6, fig. 4, pl. 7, figs 1—S. Isopoma hertae Mohanti, 1972 COMMENT. Specimens were originally described from the upper Eifelian to Givetian transitional beds in the Cantabrian Mountains, northern Spain, and these have been studied. This species is charac- terized by a circular to subpentagonal outline, weakly developed 158 M. MOHANTI AND C.H.C. BRUNTON Fig. 6 Jsopoma gryps Schmidt. Sections through the socket region of a poorly preserved specimen showing thickened valves. Greifenstein Kalk, Lower Eifelian, trench at Wiege, Greifenstein, Hessen, Germany; BD 12786, x 9. uniplication modified by a zig-zag commissure resulting from 6—7 short, anteriorly confined ribs. The ventral valve is further ornamented by a median groove originating close to the umbo. Isopoma hertae has also been recorded by Ficner & Havlicek (1978) from the Lower Givetian beds of the Celechovice area in Moravia, Czech Republic. Isopoma isiliense Rzhonsnitskaya, 1953 1953. Isopoma isiliensis Rzhonsnitskaya: 177, pl. 10, figs 12, 13. COMMENT. The only known occurrence is the original description of specimens from the Upper Frasnian of the Kuznetsk Basin, 10a 10b 10c Figs 9,10 Jsopoma lummatoniensis (Davidson). 9a—d, Lectotype, here selected (figured Davidson, 1865: pl. 14, fig. 14); dorsal, ventral, anterior and lateral views with the umbo to the right; late Givetian, Lummaton, Devon; BB 61841, x 3. 10a—d, dorsal, ventral, anterior and lateral views (with the umbo to the left); late Givetian, Lummaton, Devon; B 12802, x 3. Russia (Rzhonsnitskaya, 1953). The species is poorly characterized, but appears to be rather small and deep bodied, with 3 ribs in the ventral sulcus. Interiors are unknown. Fig. 7 Jsopoma hertae Mohanti. Dorsal, ventral, anterior and lateral TIsopoma lummatoniensis (Davidson, 1865) Figs 9-1 il; 21 (anterior uppermost) views; Portilla Formation (Eifelian to Givetian) of southern! Gantabrica, Spain: BD12734, x3. 1865 Rhynchonella lummatoniensis Davidson: 70, pl. 14, figs 14-17. Fig. 8 /sopoma hertae Mohanti. Portilla Formation (Eifelian to Givetian), Cantabrica, Spain; sections of the specimen figured by Fig. 11 /sopoma lummatoniensis (Davidson). Sections through the socket Mohanti (1972: figs 30.2, 30.3); specimen not registered, Geologisch en and hinge plate region. Lummaton Shell Bed, late Givetian, Lummaton, Mineralogisch Instituut, Rijksuniversiteit, Leiden, x 8. Devon: BB 51959, x 9. RHYNCHONELLIDE BRACHIOPOD JSOPOMA TORLEY 21953 Isopoma lummatoniensis (Davidson); Rzhonsnitskya: 176, pl. 10, figs 14, 15. TYPE SPECIMEN. BB 6184, figured by Davidson (1865: pl. 14, fig. 14), is here selected lectotype (Fig. 9a—d). COMMENT. Davidson (1865), described a series of quarries at Lummaton, about 3 miles north of Torquay, Devon. He referred to the beds as the Stringocephalus Burtini Beds. The Lummaton Shell Bed is part of this series of late Givetian fossiliferous limestones. Davidson (1882: 11) said Rigaux (1878) had recorded Rhynchonella lummatoniensis at Ferques, France. However, the extensive ecologi- cal study by Wallace (1966; 1969) in that area did not record the species, so we are doubtful about /sopoma occurring at Ferques. The species is characterized by its high ventral sulcus containing a single rib and the deep body cavity; the dorsal valve has a corresponding long narrow median groove. Davidson (1865: pl. 14, fig. 15) figured a second syntype of Rhynchonella lummatoniensis which is less deep-bodied and has two ribs in the ventral sulcus. This might be conspecific with the lectotype, but it recalls the similarly shallow specimen of /. maymyoensis described below. Large collec- tions might reveal whether these shallower specimens with more ribs are really conspecific. Rzhonsnitskya (1953: 176, pl. 10, figs 14, 15) recorded and illustrated /. lummatoniensis from the Frasnian of the Kuznetsk Basin, Russia, but internal structures of these specimens are very poorly known and generic assignment remains in doubt. 12a 12b 13a 13b 159 Figs 12-14, 20 1969 = Uncinulus subsignata Reed; Anderson et al.: 137, pl. 5, figs 18-21 (non figs 22-31). Isopoma maymyoensis sp. nov. ETYMOLOGY. The species is named from Maymyo, Burma, the region from which the material was collected. TYPE SPECIMEN. The holotype (BB 55546; figured Anderson, Boucot & Johnson, 1969: pl. 5, figs 18, 19) is from the Padaukpin Limestone (late Eifelian to early Givetian), Padaukpin, 10 miles NE of Maymyo, Central Burma. DIAGNOSIS. Jsopoma with relatively shallow body cavity and weakly developed uniplication modified by 1-3 short ribs within the sulcus; an additional pair of ribs may occur laterally; hinge plates well separated both medially and from the dorsal valve floor. COMMENT. Anderson ef al.’s (1969) description of Uncinulus subsignata included smaller specimens which are here called Isopoma maymyoensis, as well as larger specimens (Anderson et al., 1969: pl. 5, figs 22-31) which we accept as Nalivkinaria subsignata (see Mohanti, 1972: 166). The age of the /sopoma specimens, together with Nalivkinaria, was originally given as probably Eifelian, but we extend the age of the beds into the Early Givetian (Mohanti & Brunton, 1992: 11). Ecologically /sopoma maymyoensis thrived in a shallow marine subtidal benthic level-bottom environment and the associated carbonates contain a variety of shelly fossils. 13d ‘ 13e Figs 12,13 Jsopoma maymyoensis sp. nov., late Eifelian to lower Givetian, Padaukpin Limestone, Padaukpin, Burma. 12a—d, Holotype; dorsal, ventral, anterior and lateral views (note that the umbo is broken); BB 55546, x 4. 13a—d, dorsal, ventral, anterior and lateral views, x 4; 13e, detail of part of the dorsal valve, BB 55547, x 10. Fig. 14 [sopoma maymyoensis sp. nov. Sections at the sockets and hinge plates and anteriorly through the crura. Padaukpin Limestone, Burma, BB 55547, x 9. 160 15d Fig. 15 /sopoma orthoglossa (Torley). Lectotype; dorsal, ventral, anterior and lateral views (with ventral valve uppermost); Flinzkalk, Givetian, Iserlohn, SMF XVII 1164a, x 2.5 (from Schmidt, 1951: pl. 1, fig. 6). Isopoma nekhoroshevi Bublichenko, 1974 1974 Isopoma nekhoroshevi Bublichenko: 73, text—fig. 9; pl. 2, fig. 9. COMMENT. This species is from the Emsian of the Rudnogo Altai, Ural Mountains, Russia. The specimens are small, the ventral sulcus starts near the ventral umbo and ribbing is confined anteriorly, associated with the fold and sulcus. The hinge plate appears to be divided (Bublichenko, 1974: text—fig. 9) and the lack of a median septum is normal for the genus. Isopoma orthoglossa (Torley, 1908) Fig 15 1908 Camarophoria orthoglossa Torley: 29, pl. 3, figs 20, 21, pl. 4, figs 1-3. 1951 Isopoma orthoglossa (Torley); Schmidt: 87, pl. 1, figs 6a—d. COMMENT. Schmidt (1951) redescribed this species from the Flinzkalk (Upper Givetian) in the Iserlohn-Letmathe area on the east side of the river Rhine, Germany. The lectotype (Schmidt, 1951: pl. 1, fig. 6) is comparable to the wide Givetian specimens of [sopoma brachyptyctum. No information on internal structures was given by Schmidt. Further work on this species and the wider form of /. brachyptyctum from the Upper Givetian of the eastern Rhine area is needed to establish their relationships. We have studied two speci- mens from Bilveringsen (SMF XVII 478a), but have not been able to prepare sections. Isopoma ovale Xian Si-yan & Jiang Zong-long, 1978 1978 Isopoma ovale Xian & Jiang: 289, pl. 106, fig. 13. COMMENT. Jsopoma ovale is from the lower part of the Dushan Formation (Givetian), Dongyao, Xiasi, Dushan County, Guizhou, China. Externally this species somewhat resembles the wider forms of I. brachyptyctum found in the Upper Givetian strata of Germany. Xian & Jiang (1978: 289) record ‘dental plates fused with the wall of shell’. However, we have seen no evidence of dental plates as compared to simple shell wall thickening. They also report that crural plates and hinge plates are separated and the cardinal process absent. /. ovale differs from the type species in being wider in outline, having a weak sulcus and 7 to 8 anterior ribs close to the commissure. M. MOHANTI AND C.H.C. BRUNTON 16b 16d Fig. 16 /sopoma? ren Schmidt. Holotype, dorsal, ventral, anterior (x2) and lateral views; Flinzkalk, Schleddenhof bei Iserlohn; SMF XVII 1163a, x 1.7 (from Schmidt, 1951: pl. 1). Isopoma? ren Schmidt, 1951 Fig. 16 21908 Camarophoria aptycta (Schnur); Torley: 30, pl. 6, figs 4, 5. 1951 Isopoma? ren Schmidt: 88, pl. 1, fig. 4. COMMENT. Schmidt assigned her species doubtfully to Isopoma; it is from the Upper Givetian Flinzkalk in the Iserlohn-Letmathe area, Germany. The figured specimen (Schmidt, 1951: pl. 1, fig. 4) appears to be somewhat wider than /. brachyptyctum, deeper bodied and has indistinct ribs. Schmidt described a divided hinge plate, weakly curved and ventrally directed crura, and the absence of an internal median septum, all features that are consistent with/sopoma. We have seen two specimens from Schleddenhof (SMF XVII 1163b, 1163c), but have not been able to prepare sections for internal study. 17a Fig. 17 Jsopoma xestum Torley. Dorsal, ventral, anterior and lateral views; Givetian, Massenkalk, Bilveringsen, Germany; BD 12785, x 3. Fig. 18 Jsopoma xestum Torley. Sections through the specimen from Massenkalk, Germany, figured in Fig. 17, x 9. RHYNCHONELLIDE BRACHIOPOD JSOPOMA TORLEY Isopoma xestum Torley, 1934 Figs 17, 18 1934 Isopoma xestum Torley: 82, pl. 3, figs 16, 17. COMMENT. This species is from the Upper Givetian Massenkalke of Bilveringsen near Iserlohn on the east of the Rhine, Germany. The figured specimens are small and less deep than typical /. brachyptyctum and do not show ribbing. We have studied 11 speci- mens (SMF XVII 347c) and an unregistered specimen, donated by the late Dr Struve, from the Kohlenstein member of the Massenkalk at the Kohlenstein quarry in the Iserlohn Bilveringsen area (BD 12785). The sectioned specimen was not well preserved so the internal features remain poorly known and reference of the species to [sopoma remains insecure. STRATIGRAPHIC AND GEOGRAPHIC DISTRIBUTION OF ISOPOMA Twelve species of sopoma are described or commented upon above; I. aptyctum (Schnur), of supposed Frasnian age, is very poorly known, and we have not been able to study specimens, so we do not describe it here. Of these twelve reasonably established species, eight are from the Eifelian to Givetian of the Middle Devonian, and two (/. alecto (Barrande) and I. nekhoroshevi Bublichenko) from the Pragian and Emsian of the Lower Devonian are doubtfully referred to Isopoma. Two more species (/.? ren Schmidt and J. xestwm Torley), from the upper Givetian might belong to /sopoma, but they are also poorly known. We, therefore, suggest a well established stratigraphical range for sopoma in the Eifelian and Givetian, with less securely established species in later Lower Devonian rocks. Isopoma appears to be absent from the Devonian of Morocco (Drot, 1964) and Afghanistan (Durkoop, Mensink & Plodowski, 1967; Durkoop, 1970). Brice (1971), however, described specimens from Afghanistan as Kransia? cf. subsignata (Reed, 1908), and 19 161 suggested they are conspecific with specimens from Burma figured by Anderson, Boucot & Johnson (1969) as Uncinulus subsignata (Reed). We do not think Brice’s (1971) illustrations belong to what would now be called Nalivkinaria subsignata, or to either Beckmannia or [sopoma. The palaeogeographical map (Fig. 22) shows the distributions of Isopoma species. PALAEOBIOGEOGRA PHY Devonian brachiopod biogeography has been discussed in detail by Boucot (1988). Jsopoma is typically a Middle Devonian brachiopod belonging to the Rhenish-Bohemian Region of the Old World Realm (Boucot, 1984) and has Rhenish provincial affinities (Struve, 1982a). The largely warm, shallow marine environment of this biogeographic region probably had complex current circulation patterns. Apart from palaeogeography, sea-level changes and the development of reefs and banks, the shallow seas and patterns of marine circulation might have influenced the variable faunal associations of the Middle Devonian of the Rhenish-Bohemian Region. Information on the Rhenish-Bohemian Region brachiopods shows them as occurring in parts of Europe, North Africa and Asia. The Lower and Middle Devonian faunas of most of north Africa are of Rhenish-Bohemian Region type (Boucot ef al., 1983). The Jauf Formation of Lower Devonian (Pragian-Emsian) age of northwestern Saudi Arabia con- tains brachiopods and trilobites which also belong to the Rhenish-Bohemian Region of the Old World Realm (Boucot, 1984; Boucot et al., 1989). A Rhenish type of Eifelian brachiopod fauna occurs in Armenia and the Tien Shan (Boucot et al., 1988: 365). The biostratigraphy and biogeography of Devonian brachiopods in China have been described by Hou Hong-Fei (1981) and Wang Yu et al. (1984). The South China Province includes the south Tien Shan Mountains, Figs 19-21 Scanning electron micrographs of abraded valve exteriors illustrating macro-shell structures in three species of sopoma. 19, I. brachyptyctum (Schnur), Eifel, Germany; same specimen as Fig. 3; ventral valve anterolateral flank, BD 12784, x 100; 20, . maymyoensis sp. noy., Burma; ventral valve (see Fig. 13), posterior to median sulcus, BB 55547, x 50; 21, 1. lummatoniensis (Davidson); Devon, England; ventral valve, posterolateral flank, BB12802, x 40. 162 M. MOHANTI AND C.H.C. BRUNTON Fig. 22 World palaeogeographical map of the Middle Devonian (from Scotese & McKerrow, 1990) showing the distribution of Jsopoma species. A — Lower Devonian, Pragian; A — Lower Devonian, Emsian; ® — Middle Devonian, Eifelian to Givetian; © — Upper Devonian, Frasnian. 1 — north Spain (J. hertae); 2 — Devon, England (J. lummatoniensis); 3 — Eifel, Germany (1. brachyptyctum, gryps, orthoglossa, ren, xestum); 4 — Czech Republic (J. brachyptyctum, hertae, and in Pragian, I. alecto); 5 — Poland (J. brachyptyctum); 6 — west Urals (1. brachyptyctum and in Emsian, I. nekhoroshevi); 7 — east Urals U. brachyptyctum); 8 — Guizhou, China (J. brachyptyctum, ovale); 9 — Burma (I. maymyoensis); 10 — Yukon (?/. alecto); 11 — Ardennes (J. aptyctum); 12 — Kuznetsk, Russia (J. isiliensis, 21. lummatoniensis). which are on the eastward extension of the Ural-Tien Shan marine belt, and brachiopods here are similar to those in Europe, including the Urals. During the early part of the Middle Devonian, three facies- related assemblages of brachiopods existed, reflecting different palaeoecological conditions. /sopoma is associated with the Zdimir community (Hou Hong-Fei, 1981) and restricted to limestone facies bordering platform areas. The facies is characterized by reefal limestones and biostromes composed of corals and stromatoporoids, together with abundant accumulations of Zdimir shells and occa- sional occurrences of other brachiopod genera. Farther to the north, in western Nei Monggol (Inner Mongolia), Eifelian brachiopods of the Rhenish-Bohemian Region, as well as taxa with Uralian affinites, have been described by Zhang Yan (1985; 1986). This indicates a biogeographic boundary transition comparable to that observed by Nalivikin (in Boucot et al., 1988: 365) from the western Tien Shan. Camaroforia lummatoniensis, as recorded by Anderson et al. (1969: 118) from the Eifelian of western Yunnan, may belong to /sopoma. Adjacent to western Yunnan, Eifelian brachiopods with Rhenish affinites have also been described from the northern Shan State of Burma (Anderson et al., 1969). These Middle Devonian (Eifelian to Lower Givetian) shelly faunas of Padaukpin are strikingly similar to those of the Eifel region of Germany and were first described from Burma by Reed (1908). The brachiopod fauna from the Padaukpin beds can be compared to the Middle Devonian Rhenish brachiopod faunas of the European Eifel region, Germany, the southern Cantabrian Mountains, Spain, and the Holy Cross Mountains, Poland. The presence of Beckmannia and Isopoma in the Padaukpin brachiopod assemblage adds further evidence for the European Rhenish affinities of this brachiopod fauna as an eastern extension of the Rhenish- Bohemian Region of the Old World Realm. In view of the global high level of provincialism during the Eifelian, the similarity of the Middle Devonian shelly faunas of Padaukpin, Burma, to those of the distant Eifel region in Germany seems to be a biogeographic anomaly (Boucot et al., 1988), as was also emphasized by Struve (1982b). ACKNOWLEDGEMENTS. We thank Prof Dr Willi Ziegler and the late Dr W. Struve for providing specimens from the Senckenberg Museum (Frankfurt, Germany) and also for hospitality to one of us (M.M.) during a short stay at the Senckenberg Museum for the research. One of us (M.M.) is grateful to Dr C.F. Winkler-Prins for providing facilities for studying Spanish collections at the National Museum of Natural History, Leiden, Netherlands, and Dr and Mrs C. Lalau for their kind hospitality. Mohanti is thankful to Prof Dr Hou Hong-fei and Dr Chen Xiu-qin for useful discussions during a visit to China and also for providing relevant literature. We thank Dr R.T. Gratsianova for brachiopod information from Russia and Dr. B.I. Chuvashoy for supplying valuable Russian literature. We also thank Dr V.P. Kovach and Zara Frenkiel for helping with Russian translation. We are grateful to Prof A.J. Boucot, Dr Norman Savage and Mr Rex Doescher for their kind help in various ways. Mohanti thanks Mr. Prafulla Mohanti and Mr Derek Moore for their kind hospitality during visits to London. RHYNCHONELLIDE BRACHIOPOD JSOPOMA TORLEY REFERENCES Anderson, M. M., Boucot, A. J. & Johnson, J. G. 1969. Eifelian brachiopods from Padaukpin, Northern Shan States, Burma. Bulletin of the British Museum (Natural History), Geology, London, 18 (4): 105-163, 10 pls. Baranoy, V. V. 1978. Dya novykh roda rinkhonellid iz devonskikh otlozhenii seryo- vostoka SSSR. Novosti Geologii Yakutii, 4: 45-52, 1 pl. Barrande, J. 1847. Ueber die Brachiopoden der silurischen Schichten von B6hmen. 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Rushton and J.H. Powell The first Palaezoic rhytidosteid: Trucheosaurus major (Woodward, 1909) from the late Permian of Australia, and a reassessment of the Rhytidosteidae (Amphibia, Temnospondyli) C.A. Marsicano and A. Warren The rhynchonellide brachiopod /sopoma Torley and its distribution M. Mohanti and C.H.C. Brunton Bulletin of The Natural History Museum GEOLOGY SERIES Vol. 54, No. 2, November 1998